Display device having at least four overlapping display panels

ABSTRACT

To provide a display device that is suitable for increasing in size, a display device in which display unevenness is suppressed, or a display device that can display an image along a curved surface. The display device includes a first display panel and a second display panel each including a pair of substrates. The first display panel and the second display panel each include a first region which can transmit visible light, a second region which can block visible light, and a third region which can perform display. The third region of the first display panel and the first region of the second display panel overlap each other. The third region of the first display panel and the second region of the second display panel do not overlap each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/862,787, filed Apr. 30, 2020, now allowed, which is a continuation ofU.S. application Ser. No. 16/516,730, filed Jul. 19, 2019, now U.S. Pat.No. 10,642,314, which is a continuation of U.S. application Ser. No.15/473,704, filed Mar. 30, 2017, now U.S. Pat. No. 10,359,810, which isa continuation of U.S. application Ser. No. 14/616,995, filed Feb. 9,2015, now U.S. Pat. No. 9,614,022, which claims the benefit of foreignpriority applications filed in Japan as Serial No. 2014-023930 on Feb.11, 2014, and Serial No. 2014-045128 on Mar. 7, 2014, all of which areincorporated by reference.

TECHNICAL FIELD

One embodiment of the present invention relates to a display device.Furthermore, one embodiment of the present invention relates to anelectronic device including a display device.

Note that one embodiment of the present invention is not limited to theabove technical field. The technical field of one embodiment of theinvention disclosed in this specification and the like relates to anobject, a method, or a manufacturing method. In addition, one embodimentof the present invention relates to a process, a machine, manufacture,or a composition of matter. Specifically, examples of the technicalfield of one embodiment of the present invention disclosed in thisspecification include a semiconductor device, a display device, alight-emitting device, a lighting device, a power storage device, astorage device, a method for driving any of them, and a method formanufacturing any of them.

BACKGROUND ART

In recent years, larger display devices have been required. For example,a television device for home use (also referred to as a TV or atelevision receiver), digital signage, and a public information display(PID) are given. Larger digital signage, PID, and the like can providethe increased amount of information, and attract more attention whenused for advertisement or the like, so that the effectiveness of theadvertisement is expected to be increased.

In addition, for application to mobile devices, larger display deviceshave been required. In recent years, browsability of display has beenimproved by increasing the amount of information to be displayed with anincrease of a display region of a display device.

Examples of the display device include, typically, a light-emittingdevice including a light-emitting element such as an organicelectroluminescent (EL) element or a light-emitting diode (LED), aliquid crystal display device, and an electronic paper performingdisplay by an electrophoretic method or the like.

For example, in a basic structure of an organic EL element, a layercontaining a light-emitting organic compound is provided between a pairof electrodes. By voltage application to this element, thelight-emitting organic compound can emit light. A display deviceincluding such an organic EL element needs no backlight which isnecessary for liquid crystal display devices and the like; therefore,thin, lightweight, high contrast, and low power consumption displaydevices can be obtained. For example, Patent Document 1 discloses anexample of a display device including an organic EL element.

Furthermore, Patent Document 2 discloses a flexible active matrixlight-emitting device in which an organic EL element and a transistorserving as a switching element are provided over a film substrate.

REFERENCE Patent Document

-   [Patent Document 1] Japanese Published Patent Application No.    2002-324673-   [Patent Document 2] Japanese Published Patent Application No.    2003-174153

DISCLOSURE OF INVENTION

An object of one embodiment of the present invention is to provide adisplay device that is suitable for increasing in size. Another objectof one embodiment of the present invention is to provide a displaydevice in which display unevenness is suppressed. Another object of oneembodiment of the present invention is to provide a display device thatcan display an image along a curved surface.

Another object is to provide a highly browsable electronic device.Another object is to provide a highly portable electronic device.

Another object is to provide a novel display device. Another object isto provide a novel electronic device.

Note that the descriptions of these objects do not disturb the existenceof other objects. In one embodiment of the present invention, there isno need to achieve all the objects. Objects other than the above objectswill be apparent from and can be derived from the description of thespecification and the like.

One embodiment of the present invention is a display device including afirst display panel and a second display panel. The first display paneland the second display panel each include a pair of substrates. Thefirst display panel and the second display panel each include a firstregion, a second region, and a third region. The first region includes aregion which can transmit visible light. The second region includes aregion which can block visible light. The third region includes a regionwhich can perform display. The display device includes a region in whichthe third region of the first display panel and the first region of thesecond display panel overlap each other. The display device includes aregion in which the third region of the first display panel and thesecond region of the second display panel do not overlap each other.

In the above display device, it is preferable that the first displaypanel and the second display panel each include a light-emitting elementin the third region, the first display panel and the second displaypanel each include a wiring provided along part of an outer edge of thethird region in the second region, the first display panel and thesecond display panel each include a sealant provided along another partof the outer edge of the third region in the first region, and the firstregion include a region with a width of 1 mm or more and 100 mm or less.

Another embodiment of the present invention is a display deviceincluding a first display panel, a second display panel, and a thirddisplay panel. The first display panel, the second display panel, andthe third display panel each include a pair of substrates. The firstdisplay panel, the second display panel, and the third display paneleach include a first region, a second region, and a third region. Thefirst region includes a region which can transmit visible light. Thesecond region includes a region which can block visible light. The thirdregion includes a region which can perform display. The first displaypanel, the second display panel, and the third display panel eachinclude a light-emitting element in the third region. The first displaypanel, the second display panel, and the third display panel eachinclude a wiring provided along part of an outer edge of the thirdregion in the second region. The first display panel, the second displaypanel, and the third display panel each include a sealant provided alonganother part of the outer edge of the third region in the first region.The first region includes a region with a width of 1 mm or more and 100mm or less. The display device includes a region in which the thirdregion of the first display panel and the first region of the seconddisplay panel overlap each other. The display device includes a regionin which the third region of the first display panel and the secondregion of the second display panel do not overlap each other. Thedisplay device includes a region in which the third region of the firstdisplay panel and the first region of the third display panel overlapeach other. The display device includes a region in which the thirdregion of the first display panel and the second region of the thirddisplay panel do not overlap each other. The display device includes aregion in which the third region of the second display panel and thesecond region of the third display panel do not overlap each other.

The pair of substrates preferably each have flexibility.

It is preferable that the first display panel include an FPC, there be aregion in which the FPC and the second region of the first display paneloverlap each other, there be a region in which the FPC and the thirdregion of the second display panel overlap each other, and the FPC be ona side opposite to a display surface side of the second display panel.

Furthermore, it is preferable that a layer be further included, thelayer include a resin material, there be a region in which the layer andthe third region of the first display panel overlap each other, there bea region in which the layer and the third region of the second displaypanel overlap each other, the layer include a portion which has a firstrefractive index, a substrate on a display surface side of the pair ofsubstrates include a portion which has a second refractive index, and adifference between the first refractive index and the second refractiveindex be lower than or equal to 10%.

Another embodiment of the present invention is a display moduleincluding any one of the above display devices and a touch sensor.

Another embodiment of the present invention is a display moduleincluding any of the above display devices. The display module includesa first wireless module and a second wireless module. The first wirelessmodule is capable of extracting a first signal from a received wirelesssignal and is capable of supplying the first signal to the first displaypanel. The second wireless module is capable of extracting a secondsignal from a received wireless signal and is capable of supplying thesecond signal to the second display panel.

Another embodiment of the present invention is a building including anyof the above display devices or any of the above display modules. Thebuilding includes a column or a wall and the display device or thedisplay module is on the column or the wall.

Another embodiment of the present invention is an electronic deviceincluding a first display panel, a second display panel, a third displaypanel, a first support, and a second support. The second display panelhas flexibility. The first display panel, the second display panel, andthe third display panel each include a first region, a second region,and a third region. The first region is capable of transmitting visiblelight. The second region is capable of blocking visible light. The thirdregion is capable of performing display. There is a first portion inwhich the third region of the first display panel and the first regionof the second display panel overlap each other. There is a secondportion in which the third region of the second display panel and thefirst region of the third display panel overlap each other. The firstdisplay panel includes a region supported by the first support. Thethird display panel includes a region supported by the second support.The first support and the second support are capable of changing shapesbetween an opened state in which the first display panel, the seconddisplay panel, and the third display panel are on substantially the sameplane, and a folded state in which the first display panel and the thirddisplay panel are positioned to overlap each other. In the folded state,the third region of the second display panel includes a foldable regionand the first portion and the second portion each include a region whichis not foldable.

In the above electronic device, it is preferable that the first displaypanel include a first FPC, there be a region in which the first FPC andthe second region of the first display panel overlap each other, therebe a region in which the first FPC and the third region of the seconddisplay panel overlap each other, and the first FPC be on a sideopposite to a display surface side of the second display panel.

In the above electronic device, it is preferable that the second displaypanel include a second FPC, there be a region in which the second FPCand the second region of the second display panel overlap each other,there be a region in which the second FPC and the third region of thethird display panel overlap each other, and the second FPC be on a sideopposite to a display surface side of the third display panel.

In the above electronic device, it is preferable that the first displaypanel, the second display panel, and the third display panel eachinclude a touch sensor. At this time, the touch sensor preferablyincludes a transistor and a capacitor. Furthermore, at this time, thetransistor preferably includes an oxide semiconductor in a semiconductorin which a channel is formed.

One embodiment of the present invention can provide a display devicethat is suitable for increasing in size. One embodiment of the presentinvention can provide a display device in which display unevenness issuppressed. One embodiment of the present invention can provide adisplay device that can display an image along a curved surface.Alternatively, a highly browsable electronic device can be provided.Alternatively, a highly portable electronic device can be provided.

Alternatively, a novel display device (display panel) or a novelelectronic device can be provided. Note that the description of theseeffects does not disturb the existence of other effects. One embodimentof the present invention does not necessarily achieve all the aboveeffects. Other effects will be apparent from and can be derived from thedescription of the specification, the drawings, the claims, and thelike.

BRIEF DESCRIPTION OF DRAWINGS

In the accompanying drawings:

FIGS. 1A and 1B illustrate a display device according to one embodiment;

FIGS. 2A to 2C illustrate a display device according to one embodiment;

FIGS. 3A and 3B each illustrate a display device according to oneembodiment;

FIGS. 4A to 4D each illustrate a display device according to oneembodiment;

FIGS. 5A to 5D each illustrate a display device according to oneembodiment;

FIGS. 6A to 6C illustrate a display device according to one embodiment;

FIGS. 7A to 7C illustrate a display device according to one embodiment;

FIGS. 8A to 8C each illustrate a positional relation between displaypanels according to one embodiment;

FIGS. 9A and 9B illustrate application examples of a display deviceaccording to one embodiment;

FIGS. 10A and 10B illustrate a structure example of an electronic deviceincluding a display device according to one embodiment;

FIGS. 11A and 11B illustrate a structure example of an electronic deviceincluding a display device according to one embodiment;

FIGS. 12A and 12B illustrate a structure example of an electronic deviceincluding a display device according to one embodiment;

FIG. 13 illustrates a structure example of an electronic deviceincluding a display device according to one embodiment;

FIGS. 14A to 14C illustrate a touch panel according to one embodiment;

FIGS. 15A to 15C illustrate a touch panel according to one embodiment;

FIGS. 16A to 16C illustrate a touch panel according to one embodiment;

FIGS. 17A to 17C are projection drawings illustrating a structure of aninput/output device according to one embodiment;

FIG. 18 is a cross-sectional view illustrating a structure of aninput/output device according to one embodiment;

FIGS. 19A, 19B1, and 19B2 illustrate configurations and driving methodsof a sensor circuit and a converter according to one embodiment;

FIGS. 20A to 20D illustrate examples of electronic devices and lightingdevices; and

FIGS. 21A and 21B illustrate an example of an electronic device.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments will be described in detail with reference to drawings. Notethat the present invention is not limited to the description below, andit is easily understood by those skilled in the art that various changesand modifications can be made without departing from the spirit andscope of the present invention. Accordingly, the present inventionshould not be interpreted as being limited to the content of theembodiments below.

Note that in the structures of the invention described below, the sameportions or portions having similar functions are denoted by the samereference numerals in different drawings, and description of suchportions is not repeated. Further, the same hatching pattern is used forportions having similar functions, and the portions are not especiallydenoted by reference numerals in some cases.

Note that in each drawing described in this specification, the size, thelayer thickness, or the region of each component is exaggerated forclarity in some cases. Therefore, embodiments of the present inventionare not limited to such a scale.

Note that in this specification and the like, ordinal numbers such as“first”, “second”, and the like are used in order to avoid confusionamong components and do not limit the number.

Embodiment 1

In this embodiment, structure examples and application examples of adisplay device of one embodiment of the present invention are describedwith reference to drawings.

[Structure Example 1]

FIG. 1A is a schematic top view of a display panel 100 included in adisplay device of one embodiment of the present invention.

The display panel 100 includes a display region 101, and a region 110transmitting visible light and a region 120 blocking visible light thatare adjacent to the display region 101. Furthermore, the display panel100 is provided with a flexible printed circuit (FPC) 112 in the exampleillustrated in FIG. 1A.

The display region 101 includes a plurality of pixels arranged in matrixand can display an image. One or more display elements are provided ineach pixel. As the display element, typically, a light-emitting elementsuch as an organic EL element, a liquid crystal element, or the like canbe used.

In the region 110, for example, a pair of substrates included in thedisplay panel 100, a sealant for sealing the display element sandwichedbetween the pair of substrates, and the like may be provided. Here, formembers provided in the region 110, materials that transmit visiblelight are used.

In the region 120, for example, a wiring electrically connected to thepixels included in the display region 101 is provided. In addition tothe wiring, driver circuits (such as a scan line driver circuit and asignal line driver circuit) for driving the pixels may be provided.Furthermore, in the region 120, a terminal electrically connected to theFPC 112 (also referred to as a connection terminal), a wiringelectrically connected to the terminal, and the like may be provided.

A display device 10 of one embodiment of the present invention includesa plurality of such display panels 100. FIG. 1B is a schematic top viewof the display device 10 including three display panels.

Hereinafter, to distinguish the display panels from each other, the samecomponents included in the display panels from each other, or the samecomponents relating to the display panels from each other, letters areadded to reference numerals. Unless otherwise specified, “a” is added toreference numerals for a display panel and components placed on thelowest side (the side opposite to the display surface side), and to oneor more display panels and components placed thereover, “b” or lettersafter “b” in alphabetical order are added from the lower side.Furthermore, unless otherwise specified, in describing a structure inwhich a plurality of display panels is included, letters are not addedwhen a common part of the display panels or the components is described.

The display device 10 in FIG. 1B includes a display panel 100 a, adisplay panel 100 b, and a display panel 100 c.

The display panel 100 b is placed so that part of the display panel 100b overlaps an upper side (a display surface side) of the display panel100 a. Specifically, the display panel 100 b is placed so that a region110 b transmitting visible light of the display panel 100 b overlapspart of a display region 101 a of the display panel 100 a, and thedisplay region 101 a of the display panel 100 a and a region 120 bblocking visible light of the display panel 100 b do not overlap eachother.

Furthermore, the display panel 100 c is placed so that part of thedisplay panel 100 c overlaps an upper side (a display surface side) ofthe display panel 100 b. Specifically, the display panel 100 c is placedso that a region 110 c transmitting visible light of the display panel100 c overlaps part of a display region 101 b of the display panel 100b, and the display region 101 b of the display panel 100 b and a region120 c blocking visible light of the display panel 100 c do not overlapeach other.

The region 110 b transmitting visible light overlaps the display region101 a; thus, the whole display region 101 a can be visually recognizedfrom the display surface side. Similarly, the whole display region 101 bcan also be visually recognized from the display surface side when theregion 110 c overlaps the display region 101 b. Therefore, a regionwhere the display region 101 a, the display region 101 b, and thedisplay region 101 c are placed seamlessly (a region surrounded by abold dashed line in FIG. 1B) can serve as a display region 11 of thedisplay device 10.

Here, the width W of the region 110 in FIG. 1A is greater than or equalto 0.5 mm and less than or equal to 150 mm, preferably greater than orequal to 1 mm and less than or equal to 100 mm, and further preferablygreater than or equal to 2 mm and less than or equal to 50 mm. Theregion 110 serves as a sealing region, and as the width W of the region110 is larger, the distance between an end surface of the display panel100 and the display region 101 can become longer, so that entry of animpurity such as water into the display region 101 from the outside canbe effectively suppressed. In particular, in this structure example, theregion 110 is provided adjacent to the display region 101; thus, it isimportant to set the width W of the region 110 at an appropriate value.For example, in the case where an organic EL element is used as thedisplay element, the width W of the region 110 is set to be greater thanor equal to 1 mm, whereby deterioration of the organic EL element can beeffectively suppressed. Note that also in a part other than the region110, the distance between the end portion of the display region 101 andthe end surface of the display panel 100 is preferably in the aboverange.

[Structure Example 2]

In FIG. 1B, the plurality of display panels 100 overlap each other inone direction; however, a plurality of display panels 100 may overlapeach other in two directions of the vertical and horizontal directions.

FIG. 2A shows an example of the display panel 100 in which the shape ofthe region 110 is different from that in FIG. 1A. In the display panel100 in FIG. 2A, the region 110 is placed along adjacent two sides of thedisplay region 101.

FIG. 2B is a schematic perspective view of the display device 10 inwhich the display panels 100 in FIG. 2A are arranged two by two in bothvertical and horizontal directions. FIG. 2C is a schematic perspectiveview of the display device 10 when seen from a side opposite to thedisplay surface side.

In FIGS. 2B and 2C, part of the region 110 b of the display panel 100 boverlaps a region along a short side of the display region 101 a of thedisplay panel 100 a. In addition, part of the region 110 c of thedisplay panel 100 c overlaps a region along a long side of the displayregion 101 a of the display panel 100 a. Moreover, the region 110 d ofthe display panel 100 d overlaps both a region along a long side of thedisplay region 101 b of the display panel 100 b and a region along ashort side of the display region 101 c of the display panel 100 c.

Therefore, as illustrated in FIG. 2B, a region where the display region101 a, the display region 101 b, the display region 101 c, and thedisplay region 101 d are placed seamlessly can serve as the displayregion 11 of the display device 10.

Here, it is preferable that a flexible material be used for the pair ofsubstrates included in the display panel 100 and the display panel 100have flexibility. Thus, as is the case of the display panel 100 a inFIGS. 2B and 2C, part of the display panel 100 a on the FPC 112 a sideis curved when the FPC 112 a and the like are provided on the displaysurface side, whereby the FPC 112 a can be placed under the displayregion 101 b of the adjacent display panel 100 b so as to overlap withthe display region 101 b, for example. As a result, the FPC 112 a can beplaced without physical interference with the rear surface of thedisplay panel 100 b. Furthermore, when the display panel 100 a and thedisplay panel 100 b overlap and are bonded to each other, it is notnecessary to consider the thickness of the FPC 112 a; thus, thedifference in height between the top surface of the region 110 b of thedisplay panel 100 b and the top surface of the display region 101 a ofthe display panel 100 a can be reduced. As a result, the end portionover the display region 101 a of the display panel 100 b can beprevented from being visually recognized.

Moreover, each display panel 100 has flexibility, whereby the displaypanel 100 b can be curved gently so that the top surface of the displayregion 101 b of the display panel 100 b and the top surface of thedisplay region 101 a of the display panel 100 a are equal to each otherin height. Thus, the heights of the display regions can be equal to eachother except in the vicinity of the region where the display panel 100 aand the display panel 100 b overlap each other, so that the displayquality of an image displayed on the display region 11 of the displaydevice 10 can be improved.

Although, the relation between the display panel 100 a and the displaypanel 100 b is taken as an example in the above description, the samecan apply to the relation between any two adjacent display panels.

Furthermore, to reduce the step between two adjacent display panels 100,the thickness of the display panel 100 is preferably small. For example,the thickness of the display panel 100 is preferably less than or equalto 1 mm, further preferably less than or equal to 300 μm, still furtherpreferably less than or equal to 100 μm.

FIG. 3A is a schematic top view of the display device 10 in FIGS. 2B and2C when seen from the display surface side.

Here, when the region 110 of one display panel 100 does not havesufficiently high transmittance with respect to visible light (e.g.,light with a wavelength of greater than or equal to 400 nm and less thanor equal to 700 nm), luminance of a displayed image may be decreaseddepending on the number of display panels 100 overlapping the displayregions 101. For example, in a region A in FIG. 3A, one display panel100 c overlaps the display region 101 a of the display panel 100 a. In aregion B, the two display panels 100 (the display panels 100 c and 100d) overlap the display region 101 b of the display panel 100 b. In aregion C, the three display panels 100 (the display panels 100 b, 100 cand 100 d) overlap the display region 101 a of the display panel 100 a.

In this case, it is preferable that data of the displayed image becorrected so that the gray scale of the pixels is locally increaseddepending on the number of display panels 100 overlapping the displayregions 101. In this manner, a decrease in the display quality of theimage displayed on the display region 11 of the display device 10 can besuppressed.

Alternatively, the position of the display panel 100 placed in the upperportion may be shifted, whereby the number of display panels 100overlapping the display regions 101 of the lower display panels 100 canbe reduced.

In FIG. 3B, the display panel 100 c and the display panel 100 d placedon the display panel 100 a and the display panel 100 b are relativelyshifted in one direction (X direction) by the distance of the width W ofthe region 110. At this time, there are two kinds of regions: a region Din which one display panel 100 overlaps a display region 101 of anotherdisplay panel 100, and a region E in which two display panels 100overlap a display region 101 of another display panel 100.

Note that the display panel 100 may be relatively shifted in a directionperpendicular to the X direction (Y direction).

In the case where the display panel 100 placed in the upper portion isrelatively shifted, the shape of the contour of a region in which thedisplay regions 101 of the display panels 100 are combined is differentfrom a rectangular shape. Thus, in the case where the shape of thedisplay region 11 of the display device 10 is set to a rectangular shapeas illustrated in FIG. 3B, the display device 10 may be driven so thatno image is displayed on the display regions 101 of the display panels100 that are placed outside the display region 11. Here, considering thenumber of pixels in a region where an image is not displayed, morepixels than the number obtained by dividing the number of all the pixelsin the rectangular display region 11 by the number of display panels 100may be provided in the display region 101 of the display panel 100.

Although the distance of relative shift of each display panel 100 is setto an integral multiple of the width W of the region 110 in the aboveexample, the distance is not limited thereto, and may be set asappropriate in consideration of the shape of the display panel 100, theshape of the display region 11 of the display device 10, in which thedisplay panels 100 are combined, and the like.

In the display device 10 of one embodiment of the present invention, theunlimited number of display panels 100 can be connected to enlarge thesize of the display region 11 unlimitedly. For example, in the case ofusing the display device 10 for home use, the diagonal size of thedisplay region 11 may be greater than or equal to 20 inches and lessthan or equal to 100 inches, preferably greater than or equal to 40inches and less than or equal to 90 inches. Alternatively, in the caseof using the display device 10 in a portable electronic device such as atablet terminal, the diagonal size of the display region 11 may begreater than or equal to 5 inches and less than or equal to 30 inches,preferably greater than or equal to 10 inches and less than or equal to20 inches. Alternatively, in the case of using the display device 10 ina large commercial signboard or the like, the diagonal size of thedisplay region 11 can be greater than or equal to 80 inches, greaterthan or equal to 100 inches, or greater than or equal to 200 inches.

Moreover, in the display device 10 of one embodiment of the presentinvention, the resolution (the number of pixels) of the display region11 can be increased unlimitedly. For example, the resolution of thedisplay region 11 is preferably adjusted to the normalized resolution,such as HD (number of pixels: 1280×720), FHD (number of pixels:1920×1080), WQHD (number of pixels: 2560×1440), WQXGA (number of pixels:2560×1600), 4K (number of pixels: 3840×2160), or 8K (number of pixels:7680×4320). In particular, a display device with high resolution, suchas 4K, preferably 8K, or with higher resolution than 8K is preferablyused. In personal use such as portable use and home use, as theresolution is increased, the definition is increased, so that arealistic sensation, sense of depth, and the like can be increased.Furthermore, in the case of using the display device in the commercialsignboard or the like, as the resolution is increased, the amount ofinformation that can be displayed can be increased.

[Cross-Sectional Structure Example]

FIG. 4A is a schematic cross-sectional view when the two display panels100 are bonded to each other. In FIG. 4A, the FPC 112 a and an FPC 112 bare connected to the display panel 100 a and the display panel 100 b onthe display surface side, respectively.

Alternatively, as illustrated in FIG. 4B, the FPC 112 a and the FPC 112b may be connected to the display panel 100 a and the display panel 100b on a side opposite to the display surface side, respectively. Withthis structure, the end portion of the display panel 100 a positioned onthe lower side can be attached to the rear surface of the display panel100 b; thus, the attachment area can be increased and the mechanicalstrength of the attached portion can be increased.

Alternatively, as illustrated in FIGS. 4C and 4D, a light-transmittingresin layer 131 may be provided to cover the top surfaces of the displaypanel 100 a and the display panel 100 b. Specifically, the resin layer131 is preferably provided to cover the display regions of the displaypanels 100 a and 100 b and a region where the display panel 100 a andthe display panel 100 b overlap.

By providing the resin layer 131 over the plurality of display panels100, the mechanical strength of the display device 10 can be increased.In addition, the resin layer 131 is formed to have a flat surface,whereby the display quality of an image displayed on the display region11 can be increased. For example, when a coating apparatus such as aslit coater, a curtain coater, a gravure coater, a roll coater, or aspin coater is used, the resin layer 131 with high flatness can beformed.

Furthermore, a difference in refractive index between the resin layer131 and the substrate on the display surface side of the display panel100 is preferably less than or equal to 20%, further preferably lessthan or equal to 10%, still further preferably less than or equal to 5%.By using the resin layer 131 having such a refractive index, therefractive index difference between the display panel 100 and the resincan be reduced and light can be efficiently extracted outside. Inaddition, the resin layer 131 with such a refractive index is providedto cover a step portion between the display panel 100 a and the displaypanel 100 b, whereby the step portion is not easily recognized visually,and the display quality of an image displayed on the display region 11of the display device 10 can be increased.

As a material used for the resin layer 131, for example, an organicresin such as an epoxy resin, an aramid resin, an acrylic resin, apolyimide resin, a polyamide resin, or a polyamide-imide resin can beused.

Alternatively, as illustrated in FIGS. 5A and 5B, a protective substrate132 is preferably provided over the display device 10 with the resinlayer 131 provided therebetween. Here, the resin layer 131 may serve asa bonding layer for bonding the protective substrate 132 to the displaydevice 10. With the protective substrate 132, the surface of the displaydevice 10 can be protected, and moreover, the mechanical strength of thedisplay device 10 can be increased. For the protective substrate 132 ina region overlapping at least the display region 11, alight-transmitting material is used. Furthermore, the protectivesubstrate 132 in a region other than the region overlapping the displayregion 11 may have a light-blocking property not to be visuallyrecognized.

The protective substrate 132 may have a function of a touch panel. Inthe case where the display panel 100 is flexible and can be bent, theprotective substrate 132 is also preferably flexible.

Furthermore, a difference in refractive index between the protectivesubstrate 132 and the substrate on the display surface side of thedisplay panel 100 or the resin layer 131 is preferably less than orequal to 20%, further preferably less than or equal to 10%, stillfurther preferably less than or equal to 5%.

As the protective substrate 132, a plastic substrate that is formed as afilm, for example, a plastic substrate made from polyimide (PI), anaramid, polyethylene terephthalate (PET), polyethersulfone (PES),polyethylene naphthalate (PEN), polycarbonate (PC), nylon,polyetheretherketone (PEEK), polysulfone (PSF), polyetherimide (PEI),polyarylate (PAR), polybutylene terephthalate (PBT), a silicone resin,and the like, or a glass substrate can be used. The protective substrate132 is preferably flexible. The protective substrate 132 includes afiber or the like (e.g., a prepreg). Furthermore, the protectivesubstrate 132 is not limited to the resin film, and a transparentnonwoven fabric formed by processing pulp into a continuous sheet, asheet including an artificial spider's thread fiber containing proteincalled fibroin, a complex in which the transparent nonwoven fabric orthe sheet and a resin are mixed, a stack of a resin film and a nonwovenfabric containing a cellulose fiber whose fiber width is 4 nm or moreand 100 nm or less, or a stack of a resin film and a sheet including anartificial spider's thread fiber may be used.

Alternatively, as illustrated in FIGS. 5C and 5D, a resin layer 133 maybe provided on a surface opposite to the display surfaces of the displaypanel 100 a and the display panel 100 b, and a protective substrate 134may be provided with the resin layer 133 provided between the protectivesubstrate 134 and each of the display panels 100 a and 100 b. In thismanner, the display panels 100 a and 100 b are sandwiched between thetwo protective substrates, whereby the mechanical strength of thedisplay device 10 can be further increased. Furthermore, when thethicknesses of the resin layers 131 and 133 are substantially equal toeach other, and for the protective substrates 132 and 134, materialshaving thicknesses which are substantially equal to each other are used,the plurality of display panels 100 can be located at the center of thestack. For example, when the stack including the display panel 100 isbent, by locating the display panel 100 at the center in the thicknessdirection, stress in the lateral direction applied to the display panel100 by bending can be relieved, so that damage can be prevented.

As illustrated in FIGS. 5C and 5D, an opening for extracting the FPC 112a is preferably provided in the resin layer 133 and the protectivesubstrate 134, which are located on the rear surface sides of thedisplay panels 100 a and 100 b. At this time, by providing the resinlayer 133 to cover part of the FPC 112 a, the mechanical strength at aconnection portion between the display panel 100 a and the FPC 112 a canbe increased, and defects such as peeling of the FPC 112 a can besuppressed. Similarly, the resin layer 133 is preferably provided tocover part of the FPC 112 b.

Note that the resin layer 133 and the protective substrate 134, whichare provided on the side opposite to the display surface, do notnecessarily have a light-transmitting property, and a material whichabsorbs or reflects visible light may be used. When the resin layers 133and 131, or the protective substrates 134 and 132 have the samematerials, manufacturing cost can be reduced.

[Structure Example of Display Region]

Next, a structure example of the display region 101 of the display panel100 is described. FIG. 6A is a schematic top view in which a region P inFIG. 2A is enlarged, and FIG. 6B is a schematic top view in which aregion Q in FIG. 2A is enlarged.

As illustrated in FIG. 6A, in the display region 101, a plurality ofpixels 141 is arranged in matrix. In the case where the display panel100 which is capable of full color display with three colors of red,blue, and green is formed, the pixel 141 can display any of the threecolors. Alternatively, a pixel which can display white or yellow inaddition to the three colors may be provided. A region including thepixels 141 corresponds to the display region 101.

A wiring 142 a and a wiring 142 b are electrically connected to onepixel 141. The plurality of wirings 142 a each intersects with thewiring 142 b, and is electrically connected to a circuit 143 a. Theplurality of wirings 142 b is electrically connected to a circuit 143 b.One of the circuits 143 a and 143 b can function as a scan line drivercircuit, and the other can function as a signal line driver circuit. Astructure without one of the circuits 143 a and 143 b or both of themmay be employed.

In FIG. 6A, a plurality of wirings 145 electrically connected to thecircuit 143 a or the circuit 143 b is provided. The wiring 145 iselectrically connected to an FPC 123 in an unillustrated region and hasa function of supplying a signal from the outside to the circuits 143 aand 143 b.

In FIG. 6A, a region including the circuit 143 a, the circuit 143 b, andthe plurality of wirings 145 corresponds to the region 120 blockingvisible light.

In FIG. 6B, a region outside the pixel 141 provided closest to the endcorresponds to the region 110 transmitting visible light. The region 110does not include the members blocking visible light, such as the pixel141, the wiring 142 a, and the wiring 142 b. Note that in the case wherepart of the pixel 141, the wiring 142 a, or the wiring 142 b transmitsvisible light, the part of the pixel 141, the wiring 142 a, or thewiring 142 b may be provided to extend to the region 110.

Here, the width W of the region 110 indicates the narrowest width of theregion 110 provided in the display panel 100 in some cases. In the casewhere the width W of the display panel 100 varies depending on thepositions, the shortest length can be referred to as the width W. InFIG. 6B, the distance between the pixel 141 and the end surface of thesubstrate (that is, the width W of the region 110) in the verticaldirection is the same as that in the horizontal direction.

FIG. 6C is a schematic cross-sectional view taken along line A1-A2 inFIG. 6B. The display panels 100 include a pair of light-transmittingsubstrates (a substrate 151 and a substrate 152). The substrate 151 andthe substrate 152 are bonded to each other with a bonding layer 153.Here, the substrate on which the pixel 141, the wiring 142 b, and thelike are formed is referred to as the substrate 151.

As illustrated in FIGS. 6B and 6C, in the case where the pixel 141 ispositioned closest to the end of the display region 101, the width W ofthe region 110 transmitting visible light is the distance between theend portion of the substrate 151 or the substrate 152 and the endportion of the pixel 141.

Note that the end portion of the pixel 141 refers to the end portion ofthe member that is positioned closest to the end and blocks visiblelight in the pixel 141. Alternatively, in the case where alight-emitting element including a layer containing a light-emittingorganic compound between a pair of electrodes (also referred to as anorganic EL element) is used as the pixel 141, the end portion of thepixel 141 may be any of the end portion of the lower electrode, the endportion of the layer containing a light-emitting organic compound, andthe end portion of the upper electrode.

FIG. 7A shows the case where the position of the wiring 142 a isdifferent from that in FIG. 6B. FIG. 7B is a schematic cross-sectionalview taken along line B1-B2 in FIG. 7A, and FIG. 7C is a schematiccross-sectional view taken along line C1-C2 in FIG. 7A.

As illustrated in FIGS. 7A to 7C, in the case where the wiring 142 a ispositioned closest to the end of the display region 101, the width W ofthe region 110 transmitting visible light is the distance between theend portion of the substrate 151 or the substrate 152 and the endportion of the wiring 142 a. In the case where the wiring 142 atransmits visible light, the region 110 may include a region where thewiring 142 a is provided.

Here, in the case where the density of pixels provided in the displayregion 101 of the display panel 100 is high, misalignment may occur whenthe two display panels 100 are bonded.

FIG. 8A shows a positional relation between the display region 101 a ofthe display panel 100 a provided on the lower side and the displayregion 101 b of the display panel 100 b provided on the upper side, seenfrom the display surface side. FIG. 8A shows the vicinities of thecorner portions of the display regions 101 a and 101 b. Part of thedisplay region 101 a is covered with the region 110 b.

FIG. 8A shows an example in which adjacent pixels 141 a and 141 b arerelatively deviated in one direction (Y direction). The arrow in thedrawing denotes a direction in which the display panel 100 a is deviatedfrom the display panel 100 b. FIG. 8B shows an example in which theadjacent pixels 141 a and 141 b are relatively deviated in a verticaldirection and a horizontal direction (X direction and Y direction).

In the examples of FIGS. 8A and 8B, the distances deviated in thevertical direction and the horizontal direction are each shorter thanthe length of one pixel. In this case, image data of the image displayedon either one of the display regions 101 a and 101 b is correcteddepending on the deviation distance, whereby the display quality can bemaintained. Specifically, when the deviation makes the distance betweenthe pixels smaller, the data is corrected so that the gray level(luminance) of the pixels is low, and when the deviation makes thedistance between the pixels larger, the data is corrected so that thegray level (luminance) of the pixels is high. Alternatively, when thetwo pixels overlap, the data is corrected so that the pixel positionedon a lower side is not driven and the image data is shifted by onecolumn.

FIG. 8C shows an example in which the pixels 141 a and 141 b, whichshould be adjacent, are relatively deviated in one direction (Ydirection) by a distance of more than one pixel. When the deviation ofmore than one pixel occurs, the pixels are driven so that projectingpixels (pixels which are hatched) are not displayed. Note that the sameapplies to the case where the deviation direction is the X direction.

When the plurality of display panels 100 are bonded, in order tosuppress misalignment, each of the display panels 100 is preferablyprovided with an alignment marker or the like. Alternatively, aprojection and a depression may be formed on the surfaces of the displaypanels 100, and the projection and the depression may be attached toeach other in a region where the two display panels 100 overlap.

Furthermore, in consideration of alignment accuracy, it is preferablethat pixels more than the pixels to be used be placed in advance in thedisplay region 101 of the display panel 100. For example, it ispreferable that one or more, preferably three or more, furtherpreferably five or more extra pixel columns along either one or both ofa scan line and a signal line be provided in addition to the pixelcolumns used for display.

[Application Example 1]

In the display device 10 of one embodiment of the present invention, byincreasing the number of display panels 100, the area of the displayregion 11 can be increased unlimitedly. Thus, the display device 10 canbe favorably used for applications for displaying a large image, such asdigital signage and a PID.

FIG. 9A shows an example in which the display device 10 of oneembodiment of the present invention is used for a column 15 and a wall16. A flexible display panel is used as the display panel 100 includedin the display device 10, whereby the display device 10 can be placedalong a curved surface.

Here, as the number of display panels 100 included in the display device10 is increased, the circuit size of a wiring board for supplying asignal that drives each display panel 100 is increased. Moreover, as thearea of the display device 10 is increased, a longer wiring is needed;thus, signal delay easily occurs, which may adversely affect the displayquality.

Thus, each of the plurality of display panels 100 included in thedisplay device 10 is preferably provided with a wireless module thatsupplies a signal for driving the display panel 100.

FIG. 9B shows an example of a cross section of the column 15 in the casewhere the display device 10 is placed on the surface of the cylindercolumn 15. The display device 10 including the plurality of displaypanels 100 is placed between an interior member 21 and an exteriormember 22 and is curved along the surface of the column 15.

One display panel 100 is electrically connected to the wireless module150 through the FPC 112. The display panel 100 is supported by the topsurface side of a supporting member 23 provided between the interiormember 21 and the exterior member 22, and the wireless module 150 isplaced on the lower surface side of the supporting member 23. Thedisplay panel 100 and the wireless module 150 are electrically connectedto each other through the FPC 112 through an opening provided in thesupporting member 23.

In FIG. 9B, part of the exterior member 22 is provided with alight-blocking portion 26. The light-blocking portion 26 is provided tocover a region other than the display region of the display device 10,whereby the region cannot be visually recognized by a viewer.

The wireless module 150 receives a wireless signal 27 transmitted froman antenna 25 provided inside or outside the column 15. Furthermore, thewireless module 150 has a function of extracting a signal for drivingthe display panel 100 from the wireless signal 27 and supplying thesignal to the display panel 100. As the signal for driving the displaypanel 100, the power supply potential, the synchronization signal (theclock signal), the image signal, and the like are given.

For example, each of the wireless modules 150 has an identificationnumber. The wireless signal 27 transmitted from the antenna 25 includesa signal that specifies the identification number and a signal fordriving the display panel 100. When the identification number includedin the wireless signal 27 corresponds to the identification number ofthe wireless module 150, the wireless module 150 receives the signal fordriving the display panel 100 and supplies the signal to the displaypanel 100 through the FPC 112; in this manner, different images can bedisplayed on the respective display panels 100.

The wireless module 150 may be an active wireless module to which poweris supplied from the wireless signal 27, or may be a passive wirelessmodule in which a battery and the like are incorporated. In the case ofusing the passive wireless module, the incorporated battery can becharged by transmitting and receiving electric power (this operation isalso referred to as contactless power transmission, non-contact powertransmission, wireless power supply, or the like) using anelectromagnetic induction method, a magnetic resonance method, anelectric wave method, or the like.

With such a structure, even in a large display device 10, the signal fordriving each of the display panels 100 is not delayed, and the displayquality can be increased. Furthermore, the display device 10 is drivenby the wireless signal 27; thus, when the display device 10 is placed onthe wall and the column, construction for leading a wiring through thewall and the column, and the like are unnecessary, so that the displaydevice 10 can be easily placed in any locations. For the same reason,the placement position of the display device 10 can be easily changed.

Note that in the above, one wireless module 150 is connected to onedisplay panel 100; however, one wireless module 150 may be connected totwo or more display panels 100.

For example, the display device of one embodiment of the presentinvention includes at least two display panels, and includes at least afirst wireless module that extracts a first signal from a receivedwireless signal and supplies the signal to a first display panel, and asecond wireless module that extracts a second signal from the wirelesssignal and supplies the signal to a second display panel.

[Application Example 2]

Examples of an electronic device in which the display device 10 of oneembodiment of the present invention is used are described below.

FIGS. 10A and 10B are perspective views of an electronic device 50. Theelectronic device 50 includes a support 51 a, a support 51 b, thedisplay panel 100 a, the display panel 100 b, and the display panel 100c.

The support 51 a and the support 51 b are rotatably joined to each otherby a hinge 52. The display panel 100 a is supported by the support 51 a.The display panel 100 c is supported by the support 51 b. Of the threedisplay panels, at least the display panel 100 b, which is positionedbetween the display panel 100 a and the display panel 100 c, isflexible. The display panel 100 a and the display panel 100 c need notbe flexible; however, when the display panels 100 a to 100 c have thesame structure, mass productivity can be improved.

FIG. 10A shows a state in which the display panel 100 a, the displaypanel 100 b, and the display panel 100 c are substantially on the sameplane (an opened state). FIG. 10B shows a state in which the displaypanel 100 a and the display panel 100 c overlap each other (a foldedstate). The support 51 a and the support 51 b of the electronic device50 can be reversibly changed into the opened state or the folded state.

Each of the display panels included in the electronic device 50preferably includes a touch sensor. For the touch sensor, a variety oftypes such as a capacitive type, a resistive type, a surface acousticwave type, an infrared type, and an optical type can be used. Inparticular, the capacitive type is preferably used. As the touch sensor,an active matrix touch sensor including a transistor and a capacitor ispreferably used. A specific structure example of the touch sensor and atouch panel including the touch sensor is described in embodimentsbelow.

The display device included in the electronic device 50 is preferablysupported by each support so that the display device can slide. At thistime, the display device is preferably supported by each support so thatthe display device is not moved in the thickness direction. Here, thedisplay device can preferably slide in the direction in which thedisplay device is folded of the directions parallel to the displaysurface, and the display device is preferably supported by each supportso that the display device is not moved in the direction perpendicularto the folded direction. By using this supporting method, when thedisplay device in a flat state is changed into a folded state,misalignment generated in the display device depending on the distancebetween the neutral plane and the display panel can be corrected by theslide operation. As a result, damage due to stress applied to thedisplay device can be suppressed. Alternatively, one of the plurality ofsupports and the display device may be fixed not to be slid.Furthermore, part of the display device may have elasticity. Expansionand contraction of part of the display device can correct themisalignment. Furthermore, the display device may be fixed to eachsupport so that the curved portion of the display device loosens in thestate where the display device is flat. By the looseness of the displaydevice, the misalignment can be corrected.

A supporting method of the display device included in the electronicdevice 50 by each support is not particularly limited. For example, whenthe display device is sandwiched between two members that are processedto have grooves in which the display device can be fitted, the displaydevice can be supported to be slid. In the case where the display deviceand each support are fixed, for example, an attaching method, a fixingmethod with screws or the like, a mechanically fixing method in whichthe display device is sandwiched between members, or the like is used.

In the folded state in FIG. 10B, the display panel 100 b includes afolded region so that the display region has a curved surface. Here, itis preferable that a region in which the display panel 100 a and thedisplay panel 100 b overlap and a region in which the display panel 100b and the display panel 100 c overlap be not positioned in the curvedregion. In particular, in regions 110 a, 110 b, and 110 c of the displaypanels, which transmit visible light, a belt-shaped portion extending ina direction perpendicular to the direction in which the display deviceis folded is preferably not positioned in the curved region. A region inwhich the two display panels overlap has a large thickness and may havea poorer flexibility than the other region; thus, the region ispreferably not positioned in the curved portion, whereby the displaysurface can have a smooth curved surface. Furthermore, when deformationis repeatedly caused in a portion in which the two display panels arebonded to each other, the display panels may be separated from eachother. Thus, the portion is not provided in the curved portion, wherebythe reliability of the electronic device can be improved.

In the electronic device 50 of one embodiment of the present invention,the display device including the plurality of display panels issupported by the two supports. The display device can be changed inshape, for example, can be bent. For example, the display panel 100 bcan be bent so that the display surface is placed inward (referred to asinwardly bent) and so that the display surface is placed outward(referred to as outwardly bent). The electronic device 50 of oneembodiment of the present invention is highly portable when the displaydevice is in a folded state, and has high browsability in display in anopened state because of a large display region in which joints are notvisually recognized. That is, the electronic device 50 is an electronicdevice in which browsability of display and portability are improved atthe same time.

FIG. 11A is a schematic cross-sectional view taken along line D1-D2 inan opened state of the electronic device 50 in FIG. 10A. FIG. 11B is aschematic cross-sectional view taken along line E1-E2 in a folded stateof the electronic device 50 in FIG. 10B.

As illustrated in FIGS. 11A and 11B, a substrate 53 a provided with aterminal 54 a is included inside the support 51 a. Similarly, asubstrate 53 b provided with a terminal 54 b and a terminal 54 c isincluded inside the support 51 b. The display panel 100 a iselectrically connected to the terminal 54 a through the FPC 112 a. Thedisplay panel 100 b is electrically connected to the terminal 54 bthrough the FPC 112 b. The display panel 100 c is electrically connectedto the terminal 54 c through the FPC 112 c.

Furthermore, as illustrated in FIGS. 11A and 11B, a battery (a battery55 a or a battery 55 b) is preferably included inside each support. Whenthe electronic device 50 includes a plurality of batteries, the chargingfrequency can be reduced. Alternatively, the capacitance of each batterycan be reduced; thus, volume of each battery can decrease to reduce thethicknesses of the support 51 a and the support 51 b, and theportability can be improved.

Furthermore, as illustrated in FIG. 11B, in the folded state, thedisplay panel 100 b is preferably curved along curved surfaces includedin the support 51 a and the support 51 b. In this manner, in the support51 a and the support 51 b, the surfaces have a curved shape whosecurvature radius is appropriate so that a corner portion is notpositioned at the surfaces that can be in contact with the display panel100 b. As a result, it is possible to prevent the generation of aproblem in that the display panel 100 b is damaged by bending at acurvature radius smaller than an allowable value.

FIGS. 12A and 12B show an electronic device 70 whose structure isdifferent from that of the electronic device 50. The electronic device70 is mainly different from the electronic device 50 in that a support51 c is provided between the support 51 a and the support 51 b, and aplurality of display panels (display panels 100 a to 100 j) which arearranged in the horizontal and vertical directions are included.

FIG. 12A is a schematic perspective view of the electronic device 70 inthe opened state, and FIG. 12B is a schematic perspective view in thefolded state.

The support 51 a and the support 51 c are rotatably joined to each otherby a hinge 52 a. The support 51 c and the support 51 b are rotatablyjoined to each other by a hinge 52 b. The display panel 100 a and thedisplay panel 100 f are supported by the support 51 a. The display panel100 c and the display panel 100 h are supported by the support 51 c. Thedisplay panel 100 e and the display panel 100 j are supported by thesupport 51 b. At least the display panel 100 b, the display panel 100 d,the display panel 100 g, and the display panel 100 i, which are providedso as to cross over the supports, are flexible.

In the electronic device 70 of one embodiment of the present invention,part of the flexible display device is supported by the three supports.The display device can be changed in the shape, for example, can befolded. For example, the display panel 100 b and the display panel 100 gcan be folded so that the display surfaces are placed inward (referredto as inwardly bent) and so that the display surfaces are placed outward(referred to as outwardly bent). The electronic device 70 of oneembodiment of the present invention is highly portable when the displaydevice is in a folded state, and has high browsability in display in anopened state because of a large display region in which joints are notvisually recognized. That is, the electronic device 70 is an electronicdevice in which browsability of display and portability are improved atthe same time.

As illustrated in FIGS. 12A and 12B, it is preferable that a region inwhich the display panels overlap be not positioned in the curved region.In particular, in regions 110 (regions 110 a to 110 j) of the displaypanels, which transmit visible light, a belt-shaped portion extending ina direction perpendicular to the direction in which the display deviceis folded is preferably not positioned in the curved region.Furthermore, in regions 110 transmitting visible light, a belt-shapedportion extending in a direction parallel to the direction in which thedisplay device is folded may be positioned in the curved region becausethe mechanical strength against bending is relatively high.

FIG. 13 is a schematic cross-sectional view taken along line F1-F2 in afolded state of the electronic device 70 in FIG. 12B. The inside of thesupport 51 c includes a substrate 53 c like those of the support 51 aand the support 51 b. In addition, a battery 55 c is preferably includedinside the support 51 c.

The structures of the electronic devices including two or more supportsare described above; however, the electronic device may include four ormore supports. The area of the display device of one embodiment of thepresent invention is easily increased; thus, by increasing the number ofthe supports, the display area in the opened state can be larger.Moreover, the area of one support can be increased.

At least part of this embodiment can be implemented in combination withany of the embodiments described in this specification as appropriate.

Embodiment 2

In this embodiment, a display panel which can be used in a displaydevice of one embodiment of the present invention is described withreference to drawings. Here, as an example of the display panel, a touchpanel having a function as a touch sensor is described.

FIG. 14A is a top view illustrating a structure of a touch panel thatcan be used in a display device of one embodiment of the presentinvention. FIG. 14B is a cross-sectional view taken along line A-B andline C-D in FIG. 14A. FIG. 14C is a cross-sectional view taken alongline E-F in FIG. 14A.

[Top View]

A touch panel 300 described as an example in this embodiment includes adisplay portion 301 (see FIG. 14A).

The display portion 301 includes a plurality of pixels 302 and aplurality of imaging pixels 308. The imaging pixels 308 can sense atouch of a finger or the like on the display portion 301. A touch sensorcan thus be formed using the imaging pixels 308.

Each of the pixels 302 includes a plurality of sub-pixels (e.g., asub-pixel 302R). In addition, the sub-pixels are provided withlight-emitting elements and pixel circuits that can supply electricpower for driving the light-emitting elements.

The pixel circuits are electrically connected to wirings through whichselection signals are supplied and wirings through which image signalsare supplied.

Furthermore, the touch panel 300 is provided with a scan line drivercircuit 303 g(1) that can supply selection signals to the pixels 302 andan image signal line driver circuit 303 s(1) that can supply imagesignals to the pixels 302.

The imaging pixels 308 include photoelectric conversion elements andimaging pixel circuits that drive the photoelectric conversion elements.

The imaging pixel circuits are electrically connected to wirings throughwhich control signals are supplied and wirings through which powersupply potentials are supplied.

Examples of the control signals include a signal for selecting animaging pixel circuit from which a recorded imaging signal is read, asignal for initializing an imaging pixel circuit, and a signal fordetermining the time taken for an imaging pixel circuit to sense light.

The touch panel 300 is provided with an imaging pixel driver circuit 303g(2) that can supply control signals to the imaging pixels 308 and animaging signal line driver circuit 303 s(2) that reads imaging signals.

The touch panel 300 includes the region 110 transmitting visible lightalong two sides of the display portion 301.

[Cross-Sectional View]

The touch panel 300 includes a substrate 310 and a counter substrate 370that faces the substrate 310 (see FIG. 14B).

The substrate 310 is a stack in which a flexible substrate 310 b, abarrier film 310 a that prevents diffusion of impurities to thelight-emitting elements, and an adhesive layer 310 c that bonds thebarrier film 310 a to the substrate 310 b are stacked.

The counter substrate 370 is a stack including a flexible substrate 370b, a barrier film 370 a that prevents diffusion of impurities to thelight-emitting elements, and an adhesive layer 370 c that attaches thebarrier film 370 a to the substrate 370 b (see FIG. 14B).

A sealant 360 attaches the counter substrate 370 to the substrate 310.The sealant 360 has a refractive index higher than that of air, andserves as a layer which optically attaches two members (here, thecounter substrate 370 and the substrate 310) between which the sealant360 is sandwiched (hereinafter also referred to as an optical adhesivelayer). The pixel circuits and the light-emitting elements (e.g., afirst light-emitting element 350R) are provided between the substrate310 and the counter substrate 370.

[Pixel Structure]

Each of the pixels 302 includes a sub-pixel 302R, a sub-pixel 302G, anda sub-pixel 302B (see FIG. 14C). The sub-pixel 302R includes alight-emitting module 380R, the sub-pixel 302G includes a light-emittingmodule 380G, and the sub-pixel 302B includes a light-emitting module380B.

For example, the sub-pixel 302R includes the first light-emittingelement 350R and a pixel circuit that can supply electric power to thefirst light-emitting element 350R and includes a transistor 302 t (seeFIG. 14B). The light-emitting module 380R includes the firstlight-emitting element 350R and an optical element (e.g., a firstcoloring layer 367R).

The first light-emitting element 350R includes a lower electrode 351R,an upper electrode 352, and a layer 353 containing a light-emittingorganic compound between the lower electrode 351R and the upperelectrode 352 (see FIG. 14C).

The layer 353 containing a light-emitting organic compound includes alight-emitting unit 353 a, a light-emitting unit 353 b, and anintermediate layer 354 between the light-emitting units 353 a and 353 b.

The light-emitting module 380R includes the first coloring layer 367R onthe counter substrate 370. The coloring layer transmits light with aparticular wavelength and is, for example, a layer that selectivelytransmits red, green, or blue light. Alternatively, a region thattransmits light emitted from the light-emitting element as it is may beprovided.

The light-emitting module 380R, for example, includes the sealant 360that is in contact with the first light-emitting element 350R and thefirst coloring layer 367R.

The first coloring layer 367R is positioned in a region overlapping withthe first light-emitting element 350R. Accordingly, part of lightemitted from the first light-emitting element 350R passes through thesealant 360 that also serves as an optical adhesive layer and throughthe first coloring layer 367R and is emitted to the outside of thelight-emitting module 380R as indicated by arrows in FIGS. 14B and 14C.

Note that although the case where the light-emitting element is used asa display element is described here, one embodiment of the presentinvention is not limited thereto.

For example, in this specification and the like, a display element, adisplay device and a display panel, which are devices each including adisplay element, a light-emitting element, and a light-emitting device,which is a device including a light-emitting element, can employ avariety of modes or can include a variety of elements. The displayelement, the display device, the display panel, the light-emittingelement, or the light-emitting device includes at least one of anelectroluminescence (EL) element (e.g., an EL element including organicand inorganic materials, an organic EL element, and an inorganic ELelement), an LED (e.g., a white LED, a red LED, a green LED, and a blueLED), a transistor (a transistor that emits light depending on current),an electron emitter, a liquid crystal element, electronic ink, anelectrophoretic element, a grating light valve (GLV), a plasma displaypanel (PDP), a display element using micro electro mechanical system(MEMS), a digital micromirror device (DMD), a digital micro shutter(DMS), MIRASOL (registered trademark), an interferometric modulation(IMOD) element, a MEMS shutter display element, anoptical-interference-type MEMS display element, an electrowettingelement, a piezoelectric ceramic display, a display element including acarbon nanotube, and the like. Other than the above, a display mediumwhose contrast, luminance, reflectance, transmittance, or the like ischanged by electrical or magnetic action may be included. Note thatexamples of display devices using EL elements include an EL display.Examples of display devices including electron emitters include a fieldemission display (FED) and an SED-type flat panel display (SED:surface-conduction electron-emitter display). Examples of displaydevices using liquid crystal elements include a liquid crystal display(e.g., a transmissive liquid crystal display, a transflective liquidcrystal display, a reflective liquid crystal display, a direct-viewliquid crystal display, and a projection liquid crystal display).Examples of a display device including electronic ink, Electronic LiquidPowder (registered trademark), or electrophoretic elements includeelectronic paper. In the case of a transflective liquid crystal displayor a reflective liquid crystal display, some or all of pixel electrodesfunction as reflective electrodes. For example, some or all of pixelelectrodes are formed to contain aluminum, silver, or the like. In sucha case, a memory circuit such as an SRAM can be provided under thereflective electrodes, leading to lower power consumption.

[Touch Panel Structure]

The touch panel 300 includes a light-blocking layer 367BM on the countersubstrate 370. The light-blocking layer 367BM is provided so as tosurround the coloring layer (e.g., the first coloring layer 367R).

The touch panel 300 includes an anti-reflective layer 367 p positionedin a region overlapping with the display portion 301. As theanti-reflective layer 367 p, a circular polarizing plate can be used,for example.

The touch panel 300 includes an insulating film 321. The insulating film321 covers the transistor 302 t. Note that the insulating film 321 canbe used as a layer for planarizing unevenness caused by the pixelcircuits. An insulating film on which a layer that can prevent diffusionof impurities to the transistor 302 t and the like is stacked can beused as the insulating film 321.

The touch panel 300 includes the light-emitting element (e.g., the firstlight-emitting element 350R) over the insulating film 321.

The touch panel 300 includes, over the insulating film 321, a partitionwall 328 that overlaps with an end portion of the lower electrode 351R(see FIG. 14C). In addition, a spacer 329 that controls the distancebetween the substrate 310 and the counter substrate 370 is provided overthe partition wall 328.

[Structure of Image Signal Line Driver Circuit]

The image signal line driver circuit 303 s(1) includes a transistor 303t and a capacitor 303 c. Note that the driver circuit can be formed inthe same process and over the same substrate as those of the pixelcircuits. As illustrated in FIG. 14B, the transistor 303 t may include asecond gate over the insulating film 321. The second gate may beelectrically connected to a gate of the transistor 303 t, or differentpotentials may be supplied thereto. The second gate may be provided in atransistor 308 t, the transistor 302 t, or the like if necessary.

[Structure of Imaging Pixel]

The imaging pixels 308 each include a photoelectric conversion element308 p and an imaging pixel circuit for sensing light received by thephotoelectric conversion element 308 p. The imaging pixel circuitincludes a transistor 308 t.

For example, a PIN photodiode can be used as the photoelectricconversion element 308 p.

[Structures of Other Components]

The touch panel 300 includes a wiring 311 through which a signal issupplied. The wiring 311 is provided with a terminal 319. Note that anFPC 309(1) through which a signal such as an image signal or asynchronization signal is supplied is electrically connected to theterminal 319.

Note that a printed wiring board (PWB) may be attached to the FPC309(1).

Transistors formed in the same process can be used as the transistor 302t, the transistor 303 t, and the transistor 308 t, and the like.

Transistors of a bottom-gate type, a top-gate type, or the like can beused.

As a gate, a source, and a drain of a transistor, and a wiring or anelectrode included in a touch panel, a single-layer structure or alayered structure using any of metals such as aluminum, titanium,chromium, nickel, copper, yttrium, zirconium, molybdenum, silver,tantalum, and tungsten, or an alloy containing any of these metals asits main component can be used. For example, a single-layer structure ofan aluminum film containing silicon, a two-layer structure in which analuminum film is stacked over a titanium film, a two-layer structure inwhich an aluminum film is stacked over a tungsten film, a two-layerstructure in which a copper film is stacked over acopper-magnesium-aluminum alloy film, a two-layer structure in which acopper film is stacked over a titanium film, a two-layer structure inwhich a copper film is stacked over a tungsten film, a three-layerstructure in which a titanium film or a titanium nitride film, analuminum film or a copper film, and a titanium film or a titaniumnitride film are stacked in this order, a three-layer structure in whicha molybdenum film or a molybdenum nitride film, an aluminum film or acopper film, and a molybdenum film or a molybdenum nitride film arestacked in this order, and the like can be given. Note that atransparent conductive material containing indium oxide, tin oxide, orzinc oxide may be used. Copper containing manganese is preferably usedbecause controllability of a shape by etching is increased.

An oxide semiconductor is preferably used as a semiconductor in which achannel of a transistor such as the transistor 302 t, the transistor 303t, or the transistor 308 t is formed. In particular, an oxidesemiconductor having a wider band gap than silicon is preferably used. Asemiconductor material having a wider band gap and a lower carrierdensity than silicon is preferably used because off-state leakagecurrent of the transistor can be reduced.

The oxide semiconductor preferably contains at least indium (In) or zinc(Zn), for example. The oxide semiconductor further preferably containsan In-M-Zn-based oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn,La, Ce, or Hf).

As the semiconductor layer, it is particularly preferable to use anoxide semiconductor film including a plurality of crystal parts whosec-axes are aligned perpendicular to a surface on which the semiconductorlayer is formed or the top surface of the semiconductor layer and inwhich the adjacent crystal parts have no grain boundary.

There is no grain boundary in such an oxide semiconductor; therefore,generation of a crack in an oxide semiconductor film that is caused bystress when a display panel is bent is prevented. Such an oxidesemiconductor can thus be preferably used for a flexible display panelthat is used in a bent state, or the like.

The use of such materials for the semiconductor layer makes it possibleto provide a highly reliable transistor in which a change in theelectrical characteristics is suppressed.

Charge accumulated in a capacitor through a transistor can be held for along time because of the low off-state current of the transistor. Whensuch a transistor is used for a pixel, operation of a driver circuit canbe stopped while a gray scale of an image displayed in each displayregion is maintained. As a result, a display device with an extremelylow power consumption can be obtained.

Alternatively, silicon is preferably used as a semiconductor in which achannel of a transistor such as the transistor 302 t, the transistor 303t, or the transistor 308 t is formed. Although amorphous silicon may beused as silicon, silicon having crystallinity is particularly preferablyused. For example, microcrystalline silicon, polycrystalline silicon,single crystal silicon, or the like is preferably used. In particular,polycrystalline silicon can be formed at a lower temperature than singlecrystal silicon and has higher field effect mobility and higherreliability than amorphous silicon. When such a polycrystallinesemiconductor is used for a pixel, the aperture ratio of the pixel canbe improved. Even in the case where pixels are provided at extremelyhigh resolution, a gate driver circuit and a source driver circuit canbe formed over a substrate over which the pixels are formed, and thenumber of components of an electronic device can be reduced.

Here, a method for forming a flexible light-emitting panel is described.

Here, a structure including a pixel and a driver circuit or a structureincluding an optical member such as a color filter is referred to as anelement layer for convenience. An element layer includes a displayelement, for example, and may include a wiring electrically connected toa display element or an element such as a transistor used in a pixel ora circuit in addition to the display element.

Here, a support provided with an insulating surface over which anelement layer is formed is called a base material.

As a method for forming an element layer over a flexible base materialprovided with an insulating surface, there are a method in which anelement layer is formed directly over a base material, and a method inwhich an element layer is formed over a supporting base material thathas stiffness and then the element layer is separated from thesupporting base material and transferred to the base material.

In the case where a material of the base material can withstand heatingtemperature in the process for forming the element layer, it ispreferred that the element layer be formed directly over the basematerial, in which case a manufacturing process can be simplified. Atthis time, the element layer is preferably formed in a state where thebase material is fixed to the supporting base material, in which casethe transfer of the element layer in a device and between devices can beeasy.

In the case of employing the method in which the element layer is formedover the supporting base material and then transferred to the basematerial, first, a separation layer and an insulating layer are stackedover a supporting base material, and then the element layer is formedover the insulating layer. Then, the element layer is separated from thesupporting base material and then transferred to the base material. Atthis time, a material is selected such that separation at an interfacebetween the supporting base material and the separation layer, at aninterface between the separation layer and the insulating layer, or inthe separation layer occurs.

For example, it is preferred that a stack of a layer including ahigh-melting-point metal material, such as tungsten, and a layerincluding an oxide of the metal material be used as the separationlayer, and a stack of a plurality of layers, such as a silicon nitridelayer and a silicon oxynitride layer, be used over the separation layer.The use of the high-melting-point metal material is preferable becausethe degree of freedom of the process for forming the element layer canbe increased.

The separation may be performed by application of mechanical power, byetching of the separation layer, by dripping of liquid into part of theseparation interface so that it penetrates the entire separationinterface, or the like. Alternatively, separation may be performed byheating the separation interface by utilizing a difference in thethermal expansion coefficient.

The separation layer is not necessarily provided in the case whereseparation can occur at an interface between the supporting basematerial and the insulating layer. For example, glass may be used as thesupporting base material, an organic resin such as polyimide may be usedas the insulating layer, a separation trigger may be formed by locallyheating part of the organic resin by laser light or the like, andseparation may be performed at an interface between the glass and theinsulating layer. Alternatively, a metal layer may be provided betweenthe supporting base material and the insulating layer formed of anorganic resin, and separation may be performed at an interface betweenthe metal layer and the insulating layer by feeding current to the metallayer and heating the metal layer. In that case, the insulating layerformed of an organic resin can be used as a base material.

Examples of such a flexible base material include polyester resins suchas polyethylene terephthalate (PET) and polyethylene naphthalate (PEN),a polyacrylonitrile resin, a polyimide resin, a polymethyl methacrylateresin, a polycarbonate (PC) resin, a polyethersulfone (PES) resin, apolyamide resin, a cycloolefin resin, a polystyrene resin, a polyamideimide resin, and a polyvinyl chloride resin. In particular, a materialwhose thermal expansion coefficient is low, for example, lower than orequal to 30×10⁻⁶/K is preferably used, and a polyamide imide resin, apolyimide resin, PET, or the like can suitably be used. Alternatively, asubstrate in which a fibrous body is impregnated with a resin (alsoreferred to as prepreg) or a substrate whose thermal expansioncoefficient is reduced by mixing an inorganic filler with an organicresin can be used.

In the case where a fibrous body is included in the above material, ahigh-strength fiber of an organic compound or an inorganic compound isused as the fibrous body. The high-strength fiber is specifically afiber with a high tensile modulus of elasticity or a fiber with a highYoung's modulus. Typical examples thereof include a polyvinylalcohol-based fiber, a polyester-based fiber, a polyamide-based fiber, apolyethylene-based fiber, an aramid-based fiber, a polyparaphenylenebenzobisoxazole fiber, a glass fiber, and a carbon fiber. As the glassfiber, glass fiber using E glass, S glass, D glass, Q glass, or the likecan be used. These fibers may be used in a state of a woven fabric or anonwoven fabric, and a structure body in which this fibrous body isimpregnated with a resin and the resin is cured may be used as theflexible substrate. The structure body including the fibrous body andthe resin is preferably used as the flexible substrate, in which casethe reliability against bending or breaking due to local pressure can beincreased.

Note that for a display device of one embodiment of the presentinvention, an active matrix method in which an active element isincluded in a pixel or a passive matrix method in which an activeelement is not included in a pixel can be used.

In an active matrix method, as an active element (a non-linear element),not only a transistor but also various active elements (non-linearelements) can be used. For example, an metal insulator metal (MIM), athin film diode (TFD), or the like can be used. Such an element has fewnumbers of manufacturing steps; thus, the manufacturing cost can bereduced or yield can be improved. Furthermore, because the size of theelement is small, the aperture ratio can be improved, so that powerconsumption can be reduced or higher luminance can be achieved.

As a method other than the active matrix method, the passive matrixmethod in which an active element (a non-linear element) is not used maybe used. Since an active element (a non-linear element) is not used, thenumber of manufacturing steps is small, so that the manufacturing costcan be reduced or yield can be improved. Furthermore, since an activeelement (a non-linear element) is not used, the aperture ratio can beimproved, so that power consumption can be reduced or higher luminancecan be achieved, for example.

Note that an example of the case where a variety of display is performedusing the display device is shown here; however, one embodiment of thepresent invention is not limited thereto. For example, data is notnecessarily displayed. As an example, the display device may be used asa lighting device. By using the device as a lighting device, it can beused as interior lighting having an attractive design. Alternatively, itcan be used as lighting with which various directions can beilluminated. Further alternatively, it may be used as a light source,e.g., a backlight or a front light, not the display device. In otherwords, it may be used as a lighting device for the display panel.

Here, in particular, in the case where the display device of oneembodiment of the present invention is used for a television device forhome use, digital signage, and a PID, it is preferable to use a touchpanel for a display panel as described above because a device with sucha structure does not just display a still or moving image, but can beoperated by viewers intuitively. In the case where the display device ofone embodiment of the present invention is used for advertisement, theeffectiveness of the advertisement can be increased. Alternatively, inthe case where the display device of one embodiment of the presentinvention is used for providing information such as route informationand traffic information, usability can be enhanced by intuitiveoperation.

Note that in the case where a display panel does not need to function asa touch sensor, for example, in the case of using the display panel forlarge advertisements on the walls of buildings, public facilities, andthe like, the display panel may have a structure in which the structureof the touch sensor is omitted from the above structure example of thetouch panel.

Embodiment 3

In this embodiment, a display panel which can be used in the displaydevice of one embodiment of the present invention is described withreference to drawings.

Here, as an example of the display panel, a touch panel serving as atouch sensor is described.

FIGS. 15A to 15C are cross-sectional views of a touch panel 500.

The touch panel 500 includes a display portion 501 and a touch sensor595. The touch panel 500 further includes a substrate 510, a substrate570, and a substrate 590. Note that the substrate 510, the substrate570, and the substrate 590 each have flexibility.

The display portion 501 includes the substrate 510, a plurality ofpixels over the substrate 510, and a plurality of wirings 511 throughwhich signals are supplied to the pixels. The plurality of wirings 511is led to a peripheral portion of the substrate 510, and part of theplurality of wirings 511 forms a terminal 519. The terminal 519 iselectrically connected to an FPC 509(1).

[Touch Sensor]

The substrate 590 includes the touch sensor 595 and a plurality ofwirings 598 electrically connected to the touch sensor 595. Theplurality of wirings 598 is led to a peripheral portion of the substrate590, and part of the plurality of wirings 598 forms a terminal. Theterminal is electrically connected to an FPC 509(2).

As the touch sensor 595, a capacitive touch sensor can be used. Examplesof the capacitive touch sensor include a surface capacitive touch sensorand a projected capacitive touch sensor.

Examples of the projected capacitive touch sensor include a selfcapacitive touch sensor and a mutual capacitive touch sensor, whichdiffer mainly in the driving method. The use of a mutual capacitive typeis preferable because multiple points can be sensed simultaneously.

The case of using a projected capacitive touch sensor will be describedbelow.

Note that the structure of the touch sensor is not limited to the abovestructure, and a variety of sensors that can sense the proximity or thecontact of a sensing target such as a finger, can be used.

The projected capacitive touch sensor 595 includes electrodes 591 andelectrodes 592. The electrodes 591 are electrically connected to any ofthe plurality of wirings 598, and the electrodes 592 are electricallyconnected to any of the other wirings 598.

A wiring 594 electrically connects two electrodes 591 between which theelectrode 592 is positioned. The intersecting area of the electrode 592and the wiring 594 is preferably as small as possible. Such a structureallows a reduction in the area of a region where the electrodes are notprovided, reducing unevenness in transmittance. As a result, unevennessin the luminance of light penetrating the touch sensor 595 can bereduced.

Note that the electrodes 591 and the electrodes 592 can have any of avariety of shapes. For example, the plurality of electrodes 591 may beprovided such that space between the electrodes 591 are reduced as muchas possible, and the plurality of electrodes 592 may be provided with aninsulating layer sandwiched between the electrodes 591 and theelectrodes 592 and may be spaced apart from each other to form a regionnot overlapping with the electrodes 591. In that case, between twoadjacent electrodes 592, a dummy electrode that is electricallyinsulated from these electrodes is preferably provided, whereby the areaof a region having a different transmittance can be reduced.

The touch sensor 595 includes the substrate 590, the electrodes 591 andthe electrodes 592 provided in a staggered arrangement on the substrate590, an insulating layer 593 covering the electrodes 591 and theelectrodes 592, and the wiring 594 that electrically connects theadjacent electrodes 591.

An adhesive layer 597 bonds the substrate 590 to the substrate 570 suchthat the touch sensor 595 overlaps with the display portion 501.

The electrodes 591 and the electrodes 592 are formed using alight-transmitting conductive material. As the light-transmittingconductive material, a conductive oxide such as indium oxide, indium tinoxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium isadded, or graphene can be used.

The electrodes 591 and the electrodes 592 can be formed by depositing alight-transmitting conductive material on the substrate 590 by asputtering method and then removing an unnecessary portion by any ofvarious patterning techniques such as photolithography. Graphene can beformed by a CVD method or in such a manner that a solution in whichgraphene oxide is dispersed is applied and reduced.

Examples of a material for the insulating layer 593 include resins suchas acrylic and an epoxy resin, a resin having a siloxane bond, andinorganic insulating materials such as silicon oxide, siliconoxynitride, and aluminum oxide.

Furthermore, openings reaching the electrodes 591 are formed in theinsulating layer 593, and the wiring 594 electrically connects theadjacent electrodes 591. A light-transmitting conductive material can befavorably used for the wiring 594 because the aperture ratio of thetouch panel can be increased. Moreover, a material with higherconductivity than those of the electrodes 591 and 592 can be favorablyused for the wiring 594 because electric resistance can be reduced.

One electrode 592 extends in one direction, and the plurality ofelectrodes 592 is provided in the form of stripes.

The wiring 594 intersects with the electrode 592.

Adjacent electrodes 591 are provided with one electrode 592 providedtherebetween. The wiring 594 electrically connects the adjacentelectrodes 591.

Note that the plurality of electrodes 591 is not necessarily arranged inthe direction orthogonal to one electrode 592 and may be arranged tointersect with one electrode 592 at an angle of less than 90 degrees.

One wiring 598 is electrically connected to any of the electrodes 591and 592. Part of the wiring 598 serves as a terminal. For the wiring598, a metal material such as aluminum, gold, platinum, silver, nickel,titanium, tungsten, chromium, molybdenum, iron, cobalt, copper, orpalladium or an alloy material containing any of these metal materialscan be used.

Note that an insulating layer that covers the insulating layer 593 andthe wiring 594 may be provided to protect the touch sensor 595.

A connection layer 599 electrically connects the wiring 598 to the FPC509(2).

As the connection layer 599, any of anisotropic conductive films (ACF),anisotropic conductive pastes (ACP), and the like can be used.

The adhesive layer 597 has a light-transmitting property. For example, athermosetting resin or an ultraviolet curable resin can be used;specifically, an acrylic resin, a urethane resin, an epoxy resin, or aresin having a siloxane bond can be used.

Note that the FPC 509(2), the light-blocking wiring electricallyconnected to the FPC 509(2), and the like may be placed not to overlapwith the region 110 transmitting visible light.

[Display Portion]

The display portion 501 includes a plurality of pixels arranged in amatrix. Each of the pixels includes a display element and a pixelcircuit for driving the display element.

In this embodiment, an example of using an organic electroluminescentelement that emits white light as a display element will be described;however, the display element is not limited to such element.

Other than organic electroluminescent elements, for example, any ofvarious display elements such as display elements (electronic ink) thatperform display by an electrophoretic method, an electronic liquidpowder (registered trademark) method, or the like; MEMS shutter displayelements; and optical-interference-type MEMS display elements can beused. Note that a structure suitable for employed display elements canbe selected from among a variety of structures of pixel circuits.

The substrate 510 is a stack in which a flexible substrate 510 b, abarrier film 510 a that prevents diffusion of impurities tolight-emitting elements, and an adhesive layer 510 c that bonds thebarrier film 510 a to the substrate 510 b are stacked.

The substrate 570 is a stack in which a flexible substrate 570 b, abarrier film 570 a that prevents diffusion of impurities to thelight-emitting elements, and an adhesive layer 570 c that bonds thebarrier film 570 a to the substrate 570 b are stacked.

A sealant 560 bonds the substrate 570 to the substrate 510. The sealant560 has a refractive index higher than that of air. In the case ofextracting light to the sealant 560 side, the sealant 560 serves as anoptical adhesive layer. The pixel circuits and the light-emittingelements (e.g., a first light-emitting element 550R) are providedbetween the substrate 510 and the substrate 570.

[Pixel Structure]

The pixel includes a sub-pixel 502R, and the sub-pixel 502R includes alight-emitting module 580R.

The sub-pixel 502R includes the first light-emitting element 550R andthe pixel circuit that can supply electric power to the firstlight-emitting element 550R and includes a transistor 502 t. Thelight-emitting module 580R includes the first light-emitting element550R and an optical element (e.g., a first coloring layer 567R).

The first light-emitting element 550R includes a lower electrode, anupper electrode, and a layer containing a light-emitting organiccompound between the lower electrode and the upper electrode.

The light-emitting module 580R includes the first coloring layer 567R onthe light extraction side. The coloring layer transmits light with aparticular wavelength and is, for example, a layer that selectivelytransmits red, green, or blue light. Note that in another sub-pixel, aregion that transmits light emitted from the light-emitting element asit is may be provided.

In the case where the sealant 560 is provided on the light extractionside, the sealant 560 is in contact with the first light-emittingelement 550R and the first coloring layer 567R.

The first coloring layer 567R is positioned in a region overlapping withthe first light-emitting element 550R. Accordingly, part of lightemitted from the first light-emitting element 550R passes through thefirst coloring layer 567R and is emitted to the outside of thelight-emitting module 580R as indicated by an arrow in FIG. 15A.

[Structure of Display Portion]

The display portion 501 includes a light-blocking layer 567BM on thelight extraction side. The light-blocking layer 567BM is provided so asto surround the coloring layer (e.g., the first coloring layer 567R).

The display portion 501 includes an anti-reflective layer 567 ppositioned in a region overlapping with the pixels. As theanti-reflective layer 567 p, a circular polarizing plate can be used,for example.

The display portion 501 includes an insulating film 521. The insulatingfilm 521 covers the transistor 502 t. Note that the insulating film 521can be used as a layer for planarizing unevenness due to the pixelcircuit. A layered film including a layer that can prevent diffusion ofimpurities can be used as the insulating film 521. This can preventdecrease of the reliability of the transistor 502 t or the like due todiffusion of impurities.

The display portion 501 includes the light-emitting elements (e.g., thefirst light-emitting element 550R) over the insulating film 521.

The display portion 501 includes, over the insulating film 521, apartition wall 528 that overlaps with an end portion of the first lowerelectrode. In addition, a spacer that controls the distance between thesubstrate 510 and the substrate 570 is provided over the partition wall528.

[Configuration of Scan Line Driver Circuit]

A scan line driver circuit 503 g(1) includes a transistor 503 t and acapacitor 503 c. Note that the driver circuit can be formed in the sameprocess and over the same substrate as those of the pixel circuits.

[Structures of Other Components]

The display portion 501 includes the wirings 511 through which signalsare supplied. The wirings 511 are provided with the terminal 519. Notethat the FPC 509(1) through which a signal such as an image signal or asynchronization signal are supplied is electrically connected to theterminal 519.

Note that a printed wiring board (PWB) may be attached to the FPC509(1).

[Modification Example of Display Portion]

Any of various kinds of transistors can be used in the display portion501.

FIGS. 15A and 15B illustrate a structure in which bottom-gatetransistors are used in the display portion 501.

For example, a semiconductor layer containing an oxide semiconductor,amorphous silicon, or the like can be used in the transistor 502 t andthe transistor 503 t illustrated in FIG. 15A.

For example, a semiconductor layer containing polycrystalline silicon orthe like can be used in the transistor 502 t and the transistor 503 tillustrated in FIG. 15B.

A structure of the case where top-gate transistors are used in thedisplay portion 501 is illustrated in FIG. 15C.

For example, a semiconductor layer containing an oxide semiconductor,polycrystalline silicon, a transferred single crystal silicon film, orthe like can be used in the transistor 502 t and the transistor 503 t inFIG. 15C.

At least part of this embodiment can be implemented in combination withany of the other embodiments described in this specification asappropriate.

Embodiment 4

In this embodiment, a display panel which can be used in a displaydevice of one embodiment of the present invention is described withreference to drawings. Here, as an example of the display panel, a touchpanel serving as a touch sensor is described.

FIGS. 16A to 16C are cross-sectional views of a touch panel 500B.

The touch panel 500B described in this embodiment is different from thetouch panel 500 described in Embodiment 3 in that the display portion501 displays received image data to the side where the transistors areprovided and that the touch sensor is provided on the substrate 510 sideof the display portion. Different structures will be described in detailbelow, and the above description is referred to for the other similarstructures.

[Display Portion]

The display portion 501 includes a plurality of pixels arranged in amatrix. Each of the pixels includes a display element and a pixelcircuit for driving the display element.

[Pixel Structure]

A pixel includes a sub-pixel 502R, and the sub-pixel 502R includes alight-emitting module 580R.

The sub-pixel 502R includes the first light-emitting element 550R andthe pixel circuit that can supply electric power to the firstlight-emitting element 550R and includes a transistor 502 t.

The light-emitting module 580R includes the first light-emitting element550R and an optical element (e.g., the first coloring layer 567R).

The first light-emitting element 550R includes a lower electrode, anupper electrode, and a layer containing a light-emitting organiccompound between the lower electrode and the upper electrode.

The light-emitting module 580R includes the first coloring layer 567R onthe light extraction side. The coloring layer transmits light with aparticular wavelength and is, for example, a layer that selectivelytransmits red, green, or blue light. Note that in another sub-pixel, aregion that transmits light emitted from the light-emitting element asit is may be provided.

The first coloring layer 567R is positioned in a region overlapping withthe first light-emitting element 550R. The first light-emitting element550R illustrated in FIG. 16A emits light to the side where thetransistor 502 t is provided. Accordingly, part of light emitted fromthe first light-emitting element 550R passes through the first coloringlayer 567R and is emitted to the outside of the light-emitting module580R as indicated by an arrow in FIG. 16A.

[Structure of Display Portion]

The display portion 501 includes a light-blocking layer 567BM on thelight extraction side. The light-blocking layer 567BM is provided so asto surround the coloring layer (e.g., the first coloring layer 567R).

The display portion 501 includes an insulating film 521. The insulatingfilm 521 covers the transistor 502 t. Note that the insulating film 521can be used as a layer for planarizing unevenness due to the pixelcircuit. A layered film including a layer that can prevent diffusion ofimpurities can be used as the insulating film 521. This can prevent thedecrease of the reliability of the transistor 502 t or the like due todiffusion of impurities from the coloring layer 567R.

[Touch Sensor]

The touch sensor 595 is provided on the substrate 510 side of thedisplay portion 501 (see FIG. 16A).

The adhesive layer 597 is provided between the substrate 510 and thesubstrate 590 and bonds the touch sensor 595 to the display portion 501.

Note that the FPC 509(2), the light-blocking wiring electricallyconnected to the FPC 509(2), and the like may be placed not to overlapwith the region 110 transmitting visible light.

[Modification Example 1 of Display Portion]

Any of various kinds of transistors can be used in the display portion501.

FIGS. 16A and 16B illustrate a structure of the case where bottom-gatetransistors are used in the display portion 501.

For example, a semiconductor layer containing an oxide semiconductor,amorphous silicon, or the like can be used in the transistor 502 t andthe transistor 503 t illustrated in FIG. 16A.

For example, a semiconductor layer containing polycrystalline silicon orthe like can be used in the transistor 502 t and the transistor 503 tillustrated in FIG. 16B.

FIG. 16C illustrates a structure of the case where top-gate transistorsare used in the display portion 501.

For example, a semiconductor layer containing an oxide semiconductor,polycrystalline silicon, a transferred single crystal silicon film, orthe like can be used in the transistor 502 t and the transistor 503 tillustrated in FIG. 16C.

At least part of this embodiment can be implemented in combination withany of the other embodiments described in this specification asappropriate.

Embodiment 5

In this embodiment, a structure of an input/output device of oneembodiment of the present invention is described with reference to FIGS.17A to 17C and FIG. 18 .

FIGS. 17A to 17C are projection drawings illustrating a structure of aninput/output device of one embodiment of the present invention.

FIG. 17A is a projection drawing of an input/output device 600 of oneembodiment of the present invention, and FIG. 17B is a projectiondrawing illustrating a structure of a sensor unit 60U included in theinput/output device 600.

FIG. 18 is a cross-sectional view illustrating a structure of theinput/output device 600 of one embodiment of the present invention.

FIG. 18 is a cross-sectional view taken along line Z1-Z2 of theinput/output device 600 of one embodiment of the present invention inFIG. 17A.

Note that the input/output device 600 can be a touch panel.

[Structure Example of Input/Output Device]

The input/output device 600 described in this embodiment includes aflexible input device 620 and a display portion 601. The flexible inputdevice 620 includes a plurality of sensor units 60U arranged in matrixand each provided with window portions 64 transmitting visible light, ascan line G1 electrically connected to a plurality of sensor units 60Uplaced in the row direction (indicated by arrow R in the drawing), asignal line DL electrically connected to a plurality of sensor units 60Uplaced in the column direction (indicated by arrow C in the drawing),and a flexible first base material 66 supporting the sensor unit 60U,the scan line G1, and the signal line DL. The display portion 601includes a plurality of pixels 602 overlapping with the window portions64 and arranged in matrix and a flexible second base material 610supporting the pixels 602 (see FIGS. 17A to 17C).

The sensor unit 60U includes a sensor element C overlapping with thewindow portion 64 and a sensor circuit 69 electrically connected to thesensor element C (see FIG. 17B).

The sensor element C includes an insulating layer 63, and a firstelectrode 61 and a second electrode 62 between which the insulatinglayer 63 is sandwiched (see FIG. 18 ).

A selection signal is supplied to the sensor circuit 69, and the sensorcircuit 69 supplies a sensor signal DATA based on the change incapacitance of the sensor element C.

The scan line G1 can supply the selection signal, the signal line DL cansupply the sensor signal DATA, and the sensor circuit 69 is placed tooverlap with gaps between the plurality of window portions 64.

In addition, the input/output device 600 described in this embodimentincludes a coloring layer between the sensor unit 60U and the pixel 602overlapping with the window portion 64 of the sensor unit 60U.

The input/output device 600 described in this embodiment includes theflexible input device 620 including the plurality of sensor units 60U,each of which is provided with the window portions 64 transmittingvisible light, and the flexible display portion 601 including theplurality of pixels 602 overlapping with the window portions 64. Thecoloring layer is included between the window portion 64 and the pixel602.

With such a structure, the input/output device can supply a sensorsignal based on the change in the capacitance and positional informationof the sensor unit supplying the sensor signal, can display image datarelating to the positional information of the sensor unit, and can bebent. As a result, a novel input/output device with high convenience orhigh reliability can be provided.

The input/output device 600 may include a flexible substrate FPC 1 towhich a signal from the input device 620 is supplied and/or a flexiblesubstrate FPC 2 supplying a signal including image data to the displayportion 601.

In addition, a protective layer 67 p protecting the input/output device600 by preventing damage and/or an anti-reflective layer 667 p thatweakens the intensity of external light reflected by the input/outputdevice 600 may be included.

Moreover, the input/output device 600 includes a scan line drivercircuit 603 g which supplies the selection signal to a scan line of thedisplay portion 601, a wiring 611 supplying a signal, and a terminal 619electrically connected to the flexible substrate FPC 2.

Components of the input/output device 600 are described below. Note thatthese components cannot be clearly distinguished and one component alsoserves as another component or include part of another component in somecases.

For example, the input device 620 including the coloring layeroverlapping with the plurality of window portions 64 also serves as acolor filter.

Furthermore, for example, the input/output device 600 in which the inputdevice 620 overlaps the display portion 601 serves as the input device620 as well as the display portion 601.

<<Whole Structure>>

The input/output device 600 includes the input device 620 and thedisplay portion 601 (see FIG. 17A).

<<Input Device 620>>

The input device 620 includes the plurality of sensor units 60U and theflexible base material 66 supporting the sensor units. For example, theplurality of sensor units 60U is arranged in matrix with 40 rows and 15columns on the flexible base material 66.

<<Window Portion 64, Coloring Layer, and Light-Blocking Layer BM>>

The window portion 64 transmits visible light.

A coloring layer transmitting light of a predetermined color is providedto overlap with the window portion 64. For example, a coloring layer CFBtransmitting blue light, a coloring layer CFG transmitting green light,and a coloring layer CFR transmitting red light are included (see FIG.17B).

Note that, in addition to the coloring layers transmitting blue light,green light, and/or red light, coloring layers transmitting light ofvarious colors such as a coloring layer transmitting white light and acoloring layer transmitting yellow light can be included.

For a coloring layer, a metal material, a pigment, dye, or the like canbe used.

A light-blocking layer BM is provided to surround the window portions64. The light-blocking layer BM does not easily transmit light ascompared to the window portion 64.

For the light-blocking layer BM, carbon black, a metal oxide, acomposite oxide containing a solid solution of a plurality of metaloxides, or the like can be used.

The scan line G1, the signal line DL, a wiring VPI, a wiring RES, awiring VRES, and the sensor circuit 69 are provided to overlap with thelight-blocking layer BM.

Note that a light-transmitting overcoat layer covering the coloringlayer and the light-blocking layer BM can be provided.

<<Sensor Element C>>

The sensor element C includes the first electrode 61, the secondelectrode 62, and the insulating layer 63 between the first electrode 61and the second electrode 62 (see FIG. 18 ).

The first electrode 61 is formed apart from other regions, for example,is formed into an island shape. A layer that can be formed in the sameprocess as that of the first electrode 61 is preferably placed close tothe first electrode 61 so that the user of the input/output device 600does not recognize the first electrode 61. Further preferably, thenumber of the window portions 64 placed in the gap between the firstelectrode 61 and the layer placed close to the first electrode 61 isreduced as much as possible. In particular, the window portion 64 ispreferably not placed in the gap.

The second electrode 62 is provided to overlap with the first electrode61, and the insulating layer 63 is provided between the first electrode61 and the second electrode 62.

When an object whose dielectric constant is different from that of theair gets closer to the first electrode 61 or the second electrode 62 ofthe sensor element C that is put in the air, the capacitance of thesensor element C is changed. Specifically, when a finger or the likegets closer to the sensor element C, the capacitance of the sensorelement C is changed. Accordingly, the sensor element C can be used in aproximity sensor.

Alternatively, the capacitance of the sensor element C that can bechanged in shape is changed depending on the change in shape.

Specifically, when a finger or the like is in contact with the sensorelement C, and the gap between the first electrode 61 and the secondelectrode 62 becomes small, the capacitance of the sensor element C isincreased. Accordingly, the sensor element C can be used in a tactilesensor.

Furthermore, when the sensor element C is bent, and the gap between thefirst electrode 61 and the second electrode 62 becomes small, thecapacitance of the sensor element C is increased. Accordingly, thesensor element C can be used in a bend sensor.

The first electrode 61 and the second electrode 62 include a conductivematerial.

For example, an inorganic conductive material, an organic conductivematerial, a metal material, a conductive ceramic material, or the likecan be used for the first electrode 61 and the second electrode 62.

Specifically, a metal element selected from aluminum, chromium, copper,tantalum, titanium, molybdenum, tungsten, nickel, silver, and manganese;an alloy including any of the above-described metal elements; an alloyincluding any of the above-described metal elements in combination; orthe like can be used.

Alternatively, a conductive oxide such as indium oxide, indium tinoxide, indium zinc oxide, zinc oxide, or zinc oxide to which gallium isadded can be used.

Alternatively, graphene or graphite can be used. The film includinggraphene can be formed, for example, by reducing a film containinggraphene oxide. As a reducing method, a method with application of heat,a method using a reducing agent, or the like can be employed.

Alternatively, a conductive polymer can be used.

<<Sensor Circuit 69>>

The sensor circuit 69 includes transistors M1 to M3. In addition, thesensor circuit 69 includes wirings supplying a power supply potentialand a signal. For example, the signal line DL, the wiring VPI, a wiringCS, the scan line G1, the wiring RES, and the wiring VRES are included.Note that the specific structure example of the sensor circuit 69 isdescribed in detail in Embodiment 6.

Note that the sensor circuit 69 may be placed not to overlap with thewindow portion 64. For example, a wiring is placed not to overlap withthe window portion 64, whereby one side of the sensor unit 60U can bevisually recognized easily from the other side of the sensor unit 60U.

Transistors that can be formed in the same process can be used as thetransistors M1 to M3.

The transistor M1 includes a semiconductor layer. For example, for thesemiconductor layer, an element belonging to group 4, a compoundsemiconductor, or an oxide semiconductor can be used. Specifically, asemiconductor containing silicon, a semiconductor containing galliumarsenide, an oxide semiconductor containing indium, or the like can beused.

A structure of a transistor in which an oxide semiconductor is used fora semiconductor layer is described in detail in Embodiment 6.

For the wiring, a conductive material can be used.

For example, an inorganic conductive material, an organic conductivematerial, a metal material, a conductive ceramic material, or the likecan be used for the wiring. Specifically, a material which is the sameas those of the first electrode 61 and the second electrode 62 can beused.

For the scan line G1, the signal line DL, the wiring VPI, the wiringRES, and the wiring VRES, a metal material such as aluminum, gold,platinum, silver, nickel, titanium, tungsten, chromium, molybdenum,iron, cobalt, copper, or palladium, or an alloy material containing anyof these metal materials can be used.

The sensor circuit 69 may be formed on the base material 66 byprocessing a film formed over the base material 66.

Alternatively, the sensor circuit 69 formed on another base material maybe transferred to the base material 66.

Note that a manufacturing method of the sensor circuit is described indetail in Embodiment 6.

<<Base Material 66>>

For the flexible base material 66, an organic material, an inorganicmaterial, or a composite material of an organic material and aninorganic material can be used.

For the base material 66, a material with a thickness of 5 μm or moreand 2500 μm or less, preferably 5 μm or more and 680 μm or less, furtherpreferably 5 μm or more and 170 μm or less, further preferably 5 μm ormore and 45 μm or less, further preferably 8 μm or more and 25 μm orless can be used.

Furthermore, a material with which passage of impurities is inhibitedcan be preferably used for the base material 66. For example, materialswith a vapor permeability of lower than or equal to 10⁻⁵ g/m²·day,preferably lower than or equal to 10⁻⁶ g/m²·day can be favorably used.

Furthermore, materials whose coefficients of linear expansion aresubstantially equal to each other can be preferably used as thematerials included in the base material 66. For example, the coefficientof linear expansion of the materials are preferably lower than or equalto 1×10⁻³/K, further preferably lower than or equal to 5×10⁻⁵/K, andstill further preferably lower than or equal to 1×10⁻⁵/K.

Examples of the material of the base material 66 are organic materialssuch as a resin, a resin film, and a plastic film.

Examples of the material of the base material 66 are inorganic materialssuch as a metal plate and a thin glass plate with a thickness of 10 μmor more and 50 μm or less.

An example of the material of the base material 66 is a compositematerial such as a resin film to which a metal plate, a thin glassplate, or a film of an inorganic material is attached with the use of aresin layer.

An example of the material of the base material 66 is a compositematerial such as a resin or a resin film into which a fibrous orparticulate metal, glass, or inorganic material is dispersed.

The resin layer can be formed using a thermosetting resin or anultraviolet curable resin.

Specifically, a resin film or resin plate of polyester, polyolefin,polyamide, polyimide, polycarbonate, an acrylic resin, or the like canbe used.

Specifically, non-alkali glass, soda-lime glass, potash glass, crystalglass, or the like can be used.

Specifically, a metal oxide film, a metal nitride film, a metaloxynitride film, or the like can be used. For example, a silicon oxidefilm, a silicon nitride film, a silicon oxynitride film, an aluminafilm, or the like can be used.

Specifically, SUS, aluminum, or the like in which an opening portion isprovided can be used.

Specifically, an acrylic resin, a urethane resin, an epoxy resin, or aresin having a siloxane bond can be used.

For example, a stack in which a flexible base material 66 b, a barrierfilm 66 a that prevents diffusion of impurities, and a resin layer 66 cattaching the barrier film 66 a to the base material 66 b are stackedcan be preferably used for the base material 66 (see FIG. 18 ).

Specifically, a film containing a stacked-layer material of a600-nm-thick silicon oxynitride film and a 200-nm-thick silicon nitridefilm can be used as the barrier film 66 a.

Alternatively, a film including a stacked-layer material of a600-nm-thick silicon oxynitride film, a 200-nm-thick silicon nitridefilm, a 200-nm-thick silicon oxynitride film, a 140-nm-thick siliconnitride oxide film, and a 100-nm-thick silicon oxynitride film stackedin this order can be used as the barrier film 66 a.

A resin film or resin plate of polyester, polyolefin, polyamide,polyimide, polycarbonate, an acrylic resin, or the like, a stack of twoor more of the above materials, or the like can be used as the basematerial 66 b.

For example, a material that includes polyester, polyolefin, polyamide(e.g., nylon, aramid), polyimide, polycarbonate, an acrylic resin, aurethane resin, an epoxy resin, or a resin having a siloxane bond can beused for the resin layer 66 c.

<<Protective Base Material 67, Protective Layer 67 p>>

A flexible protective base material 67 and/or the protective layer 67 pcan be provided. The flexible protective base material 67 or theprotective layer 67 p protects the input device 620 by preventingdamage.

For example, a resin film or resin plate of polyester, polyolefin,polyamide, polyimide, polycarbonate, an acrylic resin, or the like, astack of two or more of the above materials, or the like can be used asthe protective base material 67.

For example, a hard coat layer or a ceramic coat layer can be used asthe protective layer 67 p. Specifically, a layer containing a UV curableresin or aluminum oxide may be formed to overlap with the secondelectrode.

<<Display Portion 601>>

The display portion 601 includes the plurality of pixels 602 arranged inmatrix (see FIG. 17C).

For example, the pixel 602 includes a sub-pixel 602B, a sub-pixel 602G,and a sub-pixel 602R, and each sub-pixel includes a display element anda pixel circuit for driving the display element.

In the pixel 602, the sub-pixel 602B is placed to overlap with thecoloring layer CFB, the sub-pixel 602G is placed to overlap with thecoloring layer CFG, and the sub-pixel 602R is placed to overlap with thecoloring layer CFR.

In this embodiment, an example of using an organic electroluminescentelement that emits white light as a display element is described;however, the display element is not limited to such element.

For example, organic electroluminescent elements that emit light ofdifferent colors may be included in sub-pixels so that the light ofdifferent colors can be emitted from the respective sub-pixels.

<<Base Material 610>>

For the base material 610, a flexible material can be used. For example,the material that can be used for the base material 66 can be used forthe base material 610.

For example, a stack in which a flexible base material 610 b, a barrierfilm 610 a that prevents diffusion of impurities, and a resin layer 610c attaching the barrier film 610 a to the base material 610 b arestacked can be preferably used for the base material 610 (see FIG. 18 ).

<<Sealant 660>>

A sealant 660 bonds the base material 66 to the base material 610. Thesealant 660 has a refractive index higher than that of air. In the caseof extracting light to the sealant 660 side, the sealant 660 serves asan optical adhesive layer.

The pixel circuits and the light-emitting elements (e.g., alight-emitting element 650R) are provided between the base material 610and the base material 66.

<<Pixel Structure>>

The sub-pixel 602R includes a light-emitting module 680R.

The sub-pixel 602R includes the light-emitting element 650R and thepixel circuit that can supply electric power to the light-emittingelement 650R and includes a transistor 602 t. Furthermore, thelight-emitting module 680R includes the light-emitting element 650R andan optical element (e.g., a coloring layer CFR).

The light-emitting element 650R includes a lower electrode, an upperelectrode, and a layer containing a light-emitting organic compoundbetween the lower electrode and the upper electrode.

The light-emitting module 680R includes the coloring layer CFR on thelight extraction side. The coloring layer transmits light of aparticular wavelength and is, for example, a layer that selectivelytransmits light of red, green, or blue color. Other sub-pixels may beplaced to overlap with the window portion in which the coloring layer isnot provided, whereby light from the light-emitting element will beemitted not through the coloring layer.

In the case where the sealant 660 is provided on the light extractionside, the sealant 660 is in contact with the light-emitting element 650Rand the coloring layer CFR.

The coloring layer CFR is positioned in a region overlapping with thelight-emitting element 650R. Accordingly, part of light emitted from thelight-emitting element 650R passes through the coloring layer CFR and isemitted to the outside of the light-emitting module 680R as indicated byan arrow in FIG. 18 .

The light-blocking layer BM is provided to surround the coloring layer(e.g., the coloring layer CFR).

<<Configuration of Pixel Circuit>>

An insulating film 621 covering the transistor 602 t included in thepixel circuit is provided. The insulating film 621 can be used as alayer for planarizing unevenness caused by the pixel circuits. A stackedfilm including a layer that can suppress diffusion of impurities can beused as the insulating film 621. This can suppress deterioration of thereliability of the transistor 602 t or the like by diffusion ofimpurities.

The lower electrode is placed over the insulating film 621, and apartition wall 628 is provided over the insulating film 621 to cover anend portion of the lower electrode.

A layer containing a light-emitting organic compound is sandwichedbetween the lower electrode and the upper electrode, whereby alight-emitting element (e.g., the light-emitting element 650R) isformed. The pixel circuit supplies power to the light-emitting element.

In addition, a spacer that controls a gap between the base material 66and the base material 610 is provided over the partition wall 628.

<<Structure of Scan Line Driver Circuit>>

The scan line driver circuit 603 g includes a transistor 603 t and acapacitor 603 c. Note that transistors that can be formed in the sameprocess and on the same substrate as those of the pixel circuit can beused in the driver circuit.

<<Converter CONV>>

Various circuits that can convert the sensor signal DATA supplied fromthe sensor unit 60U and supply the converted signal to the FPC 1 can beused as a converter CONV (see FIG. 17A and FIG. 18 ).

For example, a transistor M4 shown in FIG. 19A can be used in theconverter CONV.

<<Structures of Other Components>>

The display portion 601 includes an anti-reflective layer 667 ppositioned in a region overlapping with the pixels. As theanti-reflective layer 667 p, a circular polarizing plate can be used,for example.

The display portion 601 includes the wirings 611 through which signalsare supplied. The wirings 611 are provided with the terminal 619. Notethat the flexible substrate FPC 2 through which a signal such as animage signal or a synchronization signal are supplied is electricallyconnected to the terminal 619.

Note that a printed wiring board (PWB) may be attached to the flexiblesubstrate FPC 2.

The display portion 601 includes wirings such as scan lines, signallines, and power supply lines. Any of various conductive films can beused as the wirings.

Specifically, a metal element selected from aluminum, chromium, copper,tantalum, titanium, molybdenum, tungsten, nickel, yttrium, zirconium,silver, and manganese; an alloy including any of the above-describedmetal elements; an alloy including any of the above-described metalelements in combination; or the like can be used. In particular, one ormore elements selected from aluminum, chromium, copper, tantalum,titanium, molybdenum, and tungsten are preferably included. Inparticular, an alloy of copper and manganese is suitably used inmicrofabrication with the use of a wet etching method.

Specifically, a two-layer structure in which a titanium film is stackedover an aluminum film, a two-layer structure in which a titanium film isstacked over a titanium nitride film, a two-layer structure in which atungsten film is stacked over a titanium nitride film, a two-layerstructure in which a tungsten film is stacked over a tantalum nitridefilm or a tungsten nitride film, a three-layer structure in which atitanium film, an aluminum film, and a titanium film are stacked in thisorder, or the like can be used.

Specifically, a stacked structure in which a film of a metal selectedfrom titanium, tantalum, tungsten, molybdenum, chromium, neodymium, andscandium, an alloy film including metals selected from the above metals,or a film including a nitride of a metal selected from the above metalsis stacked over an aluminum film can be used.

Alternatively, a light-transmitting conductive material including indiumoxide, tin oxide, or zinc oxide may be used.

At least part of this embodiment can be implemented in combination withany of the other embodiments described in this specification asappropriate.

Embodiment 6

In this embodiment, a configuration and a driving method of the sensorcircuit that can be used in the sensor unit of the input/output deviceof one embodiment of the present invention is described with referenceto FIGS. 19A, 19B1, and 19B2.

FIGS. 19A, 19B1, and 19B2 illustrate a configuration and a drivingmethod of the sensor circuit 69 and the converter CONV of one embodimentof the present invention.

FIG. 19A is a circuit diagram illustrating configurations of the sensorcircuit 69 and the converter CONV of one embodiment of the presentinvention, and FIGS. 19B1 and 19B2 are timing charts illustratingdriving methods.

The sensor circuit 69 of one embodiment of the present inventionincludes the first transistor M1 whose gate is electrically connected tothe first electrode 61 of the sensor element C and whose first electrodeis electrically connected to the wiring VPI that can supply, forexample, a ground potential (see FIG. 19A).

Furthermore, the second transistor M2 whose gate is electricallyconnected to the scan line G1 that can supply a selection signal, whosefirst electrode is electrically connected to a second electrode of thefirst transistor M1, and whose second electrode is electricallyconnected to the signal line DL that can supply, for example, the sensorsignal DATA may be included.

Furthermore, the third transistor M3 whose gate is electricallyconnected to the wiring RES that can supply a reset signal, whose firstelectrode is electrically connected to the first electrode 61 of thesensor element C, and whose second electrode is electrically connectedto the wiring VRES that can supply, for example, a ground potential maybe included.

The capacitance of the sensor element C is changed when an object getscloser to the first electrode 61 or the second electrode 62 or when agap between the first electrode 61 and the second electrode 62 ischanged, for example. Thus, the sensor unit 60U can supply the sensorsignal DATA based on the change in the capacitance of the sensor elementC.

Furthermore, the sensor unit 60U includes the wiring CS that can supplya control signal for controlling the potential of the second electrode62 of the sensor element C.

Note that a node at which the first electrode 61 of the sensor elementC, the gate of the first transistor M1, and the first electrode of thethird transistor are electrically connected to each other is referred toas a node A.

The wiring VRES and the wiring VPI each can supply a ground potential,for example, and the wiring VPO and the wiring BR each can supply a highpower supply potential, for example.

Furthermore, the wiring RES can supply a reset signal, the scan line G1can supply a selection signal, and the wiring CS can supply a controlsignal for controlling the potential of the second electrode 62 of thesensor element C.

Furthermore, the signal line DL can supply the sensor signal DATA, and aterminal OUT can supply a signal converted based on the sensor signalDATA.

Any of various circuits that can convert the sensor signal DATA andsupply the converted signal to the terminal OUT can be used as theconverter CONV. For example, a source follower circuit, a current mirrorcircuit, or the like may be formed by the electrical connection betweenthe converter CONV and the sensor circuit 69.

Specifically, by using the converter CONV including the transistor M4, asource follower circuit can be formed (see FIG. 19A). Note that atransistor that can be formed in the same process as those of the firsttransistor M1 to the third transistor M3 may be used as the transistorM4.

The transistors M1 to M3 each include a semiconductor layer. Forexample, for the semiconductor layer, an element belonging to group 4, acompound semiconductor, or an oxide semiconductor can be used.Specifically, a semiconductor containing silicon, a semiconductorcontaining gallium arsenide, an oxide semiconductor containing indium,or the like can be used.

A structure of a transistor in which an oxide semiconductor is used fora semiconductor layer is described in detail in Embodiment 5.

<Driving Method of Sensor Circuit 69>

A driving method of the sensor circuit 69 is described.

<<First Step>>

In a first step, a reset signal that turns on and then turns off thethird transistor is supplied to the gate, and the potential of the firstelectrode 61 of the sensor element C is set to a predetermined potential(see a period T1 in FIG. 19B1).

Specifically, the reset signal is supplied from the wiring RES. Thethird transistor to which the reset signal is supplied sets thepotential of the node A to a ground potential, for example (see FIG.19A).

<<Second Step>>

In a second step, a selection signal that turns on the second transistorM2 is supplied to the gate of the second transistor M2, and the secondelectrode of the first transistor is electrically connected to thesignal line DL.

Specifically, the selection signal is supplied from the scan line G1.Through the second transistor M2 to which the selection signal issupplied, the second electrode of the first transistor is electricallyconnected to the signal line DL (see a period T2 in FIG. 19B1).

<<Third Step>>

In a third step, a control signal is supplied to the second electrode ofthe sensor element C, and a potential changed based on the controlsignal and the capacitance of the sensor element C is supplied to thegate of the first transistor M1.

Specifically, a rectangular wave control signal is supplied from thewiring CS. By supplying the rectangular wave control signal to thesecond electrode 62 of the sensor element C, the potential of the node Ais increased based on the capacitance of the sensor element C (see thelatter half in the period T2 in FIG. 19B1).

For example, in the case where the sensor element is put in the air,when an object whose dielectric constant is higher than that of the airis placed closer to the second electrode 62 of the sensor element C, thecapacitance of the sensor element C is apparently increased.

Thus, the change in the potential of the node A due to the rectangularwave control signal becomes smaller than that in the case where anobject whose dielectric constant is higher than that of the air isplaced is not placed closer (see a solid line in FIG. 19B2).

<<Fourth Step>>

In a fourth step, a signal obtained by the change in the potential ofthe gate of the first transistor M1 is supplied to the signal line DL.

For example, a change in current due to the change in the potential ofthe gate of the first transistor M1 is supplied to the signal line DL.

The converter CONV converts the change in the current flowing throughthe signal line DL into a change in voltage and outputs the voltage.

<<Fifth Step>>

In a fifth step, a selection signal for turning off the secondtransistor M2 is supplied to the gate of the second transistor M2.

At least part of this embodiment can be implemented in combination withany of the embodiments described in this specification as appropriate.

Embodiment 7

In this embodiment, examples of an electronic device and a lightingdevice that include the display device of one embodiment of the presentinvention are described below with reference to drawings.

As examples of electronic devices including a display device withflexibility, the following can be given: television devices (also calledtelevisions or television receivers), monitors of computers or the like,digital cameras, digital video cameras, digital photo frames, mobilephones (also called cellular phones or mobile phone devices), portablegame machines, mobile phones, audio reproducing devices, and large gamemachines such as pachinko machines.

In addition, a lighting device or a display device can be incorporatedalong a curved inside/outside wall surface of a house or a building or acurved interior/exterior surface of a car.

FIG. 20A illustrates an example of a mobile phone. A mobile phone 7400is provided with a display portion 7402 incorporated in a housing 7401,an operation button 7403, an external connection port 7404, a speaker7405, a microphone 7406, and the like. Note that the mobile phone 7400is manufactured using the display device in the display portion 7402.

When the display portion 7402 of the mobile phone 7400 illustrated inFIG. 20A is touched with a finger or the like, data can be input to themobile phone 7400. In addition, operations such as making a call andinputting text can be performed by touch on the display portion 7402with a finger or the like.

The power can be turned on or off with the operation button 7403. Inaddition, types of images displayed on the display portion 7402 can beswitched: for example, switching images from a mail creation screen to amain menu screen is performed with the operation button 7403.

Here, the display portion 7402 includes the display device of oneembodiment of the present invention. Thus, the mobile phone can have acurved display portion and high reliability.

FIG. 20B illustrates an example of a wristband-type display device. Aportable display device 7100 includes a housing 7101, a display portion7102, an operation button 7103, and a sending and receiving device 7104.

The portable display device 7100 can receive a video signal with thesending and receiving device 7104 and can display the received video onthe display portion 7102. In addition, with the sending and receivingdevice 7104, the portable display device 7100 can send an audio signalto another receiving device.

With the operation button 7103, power ON/OFF, switching displayedvideos, adjusting volume, and the like can be performed.

Here, the display portion 7102 includes the display device of oneembodiment of the present invention. Thus, the mobile display device canhave a curved display portion and high reliability.

FIGS. 20C and 20D illustrate examples of lighting devices. Lightingdevices 7210 and 7220 each include a stage 7201 provided with anoperation switch 7203 and a light-emitting portion supported by thestage 7201.

A light-emitting portion 7212 included in the lighting device 7210illustrated in FIG. 20C has two convex-curved light-emitting portionssymmetrically placed. Thus, light radiates from the lighting device7210.

The lighting device 7220 illustrated in FIG. 20D includes aconcave-curved light-emitting portion 7222. This is suitable forilluminating a specific range because light emitted from thelight-emitting portion 7222 is collected to the front of the lightingdevice 7220.

The light-emitting portion included in each of the lighting devices 7210and 7220 is flexible; thus, the light-emitting portion may be fixed on aplastic member, a movable frame, or the like so that an emission surfaceof the light-emitting portion can be bent freely depending on theintended use.

The light-emitting portions included in the lighting devices 7210 and7220 each include the display device of one embodiment of the presentinvention. Thus, the lighting devices can have curved display portionsand high reliability.

FIG. 21A illustrates an example of a portable display device. A displaydevice 7300 includes a housing 7301, a display portion 7302, operationbuttons 7303, a display portion pull 7304, and a control portion 7305.

The display device 7300 includes a rolled flexible display portion 7302in the cylindrical housing 7301. The display portion 7302 includes afirst substrate provided with a light-blocking layer and the like and asecond substrate provided with a transistor and the like. The displayportion 7302 is rolled so that the second substrate is positionedagainst an inner wall of the housing 7301.

The display device 7300 can receive a video signal with the controlportion 7305 and can display the received video on the display portion7302. In addition, a battery is included in the control portion 7305.Moreover, a connector may be included in the control portion 7305 sothat a video signal or power can be supplied directly.

With the operation buttons 7303, power ON/OFF, switching of displayedvideos, and the like can be performed.

FIG. 21B illustrates a state in which the display portion 7302 is pulledout with the display portion pull 7304. Videos can be displayed on thedisplay portion 7302 in this state. In addition, the operation buttons7303 on the surface of the housing 7301 allow one-handed operation.

Note that a reinforcement frame may be provided for an edge portion ofthe display portion 7302 in order to prevent the display portion 7302from being curved when pulled out.

Note that in addition to this structure, a speaker may be provided forthe housing so that sound is output with an audio signal receivedtogether with a video signal.

The display portion 7302 includes the display device of one embodimentof the present invention. Thus, the display portion 7302 is a flexible,highly reliable display device, which makes the display device 7300lightweight and highly reliable.

It is needless to say that the embodiment of the present invention isnot limited to the above-described electronic devices and lightingdevices as long as the display device of one embodiment of the presentinvention is included.

The structures, methods, and the like described in this embodiment canbe used in appropriate combination with any of the structures, methods,and the like described in the other embodiments.

This application is based on Japanese Patent Application serial no.2014-023930 filed with Japan Patent Office on Feb. 11, 2014, andJapanese Patent Application serial no. 2014-045128 filed with JapanPatent Office on Mar. 7, 2014, the entire contents of which are herebyincorporated by reference.

EXPLANATION OF REFERENCE

10: display device, 11: display region, 15: column, 16: wall, 21:interior member, 22: exterior member, 23: supporting member, 25:antenna, 26: light-blocking portion, 27: wireless signal, 50: electronicdevice, 51 a: support, 51 b: support, 51 c: support, 52: hinge, 52 a:hinge, 52 b: hinge, 53 a: substrate, 53 b: substrate, 53 c: substrate,54 a: terminal, 54 b: terminal, 54 c: terminal, 55 a: battery, 55 b:battery, 55 c: battery, 60U: sensor unit, 61: electrode, 62: electrode,63: insulating layer, 64: window portion, 66: base material, 66 a:barrier film, 66 b: base material, 66 c: resin layer, 67: protectivebase material, 67 p: protective layer, 69: sensor circuit, 70:electronic device, 100: display panel, 100 a: display panel, 100 b:display panel, 100 c: display panel, 100 d: display panel, 100 e:display panel, 100 f: display panel, 100 g: display panel, 100 h:display panel, 100 i: display panel, 100 j: display panel, 101: displayregion, 101 a: display region, 101 b: display region, 101 c: displayregion, 101 d: display region, 110: region, 110 a: region, 110 b:region, 110 c: region, 110 d: region, 112: FPC, 112 a: FPC, 112 b: FPC,112 c: FPC, 120: region, 120 b: region, 120 c: region, 123: FPC, 131:resin layer, 132: protective substrate, 133: resin layer, 134:protective substrate, 141: pixel, 141 a: pixel, 141 b: pixel, 142 a:wiring, 142 b: wiring, 143 a: circuit, 143 b: circuit, 145: wiring, 150:wireless module, 151: substrate, 152: substrate, 153: bonding layer,300: touch panel, 301: display portion, 302: pixel, 302B: sub-pixel,302G: sub-pixel, 302R: sub-pixel, 302 t: transistor, 303 c: capacitor,303 g(1): scan line driver circuit, 303 g(2): imaging pixel drivercircuit, 303 s(1): image signal line driver circuit, 303 s(2): imagingsignal line driver circuit, 303 t: transistor, 308: imaging pixel, 308p: photoelectric conversion element, 308 t: transistor, 309: FPC, 310:substrate, 310 a: barrier film, 310 b: substrate, 310 c: bonding layer,311: wiring, 319: terminal, 321: insulating film, 328: partition wall,329: spacer, 350R: first light-emitting element, 351R: lower electrode,352: upper electrode, 353: layer, 353 a: light-emitting unit, 353 b:light-emitting unit, 354: intermediate layer, 360: sealant, 367BM:light-blocking layer, 367 p: anti-reflective layer, 367R: first coloringlayer, 370: counter substrate, 370 a: barrier film, 370 b: substrate,370 c: bonding layer, 380B: light-emitting module, 380G: light-emittingmodule, 380R: light-emitting module, 500: touch panel, 500B: touchpanel, 501: display portion, 502R: sub-pixel, 502 t: transistor, 503 c:capacitor, 503 g: scan line driver circuit, 503 t: transistor, 509: FPC,510: substrate, 510 a: barrier film, 510 b: substrate, 510 c: bondinglayer, 511: wiring, 519: terminal, 521: insulating film, 528: partitionwall, 550R: first light-emitting element, 560: sealant, 567BM:light-blocking layer, 567 p: anti-reflective layer, 567R: first coloringlayer, 570: substrate, 570 a: barrier film, 570 b: substrate, 570 c:bonding layer, 580R: light-emitting module, 590: substrate, 591:electrode, 592: electrode, 593: insulating layer, 594: wiring, 595:touch sensor, 597: bonding layer, 598: wiring, 599: connection layer,600: input/output device, 601: display portion, 602: pixel, 602B:sub-pixel, 602G: sub-pixel, 602R: sub-pixel, 602 t: transistor, 603 c:capacitor, 603 g: scan line driver circuit, 603 t: transistor, 610: basematerial, 610 a: barrier film, 610 b: base material, 610 c: resin layer,611: wiring, 619: terminal, 620: input device, 621: insulating film,628: partition wall, 650R: light-emitting element, 660: sealant, 667 p:anti-reflective layer, 680R: light-emitting module, 7100: portabledisplay device, 7101: housing, 7102: display portion, 7103: operationbutton, 7104: sending and receiving device, 7201: stage, 7203: operationswitch, 7210: lighting device, 7212: light-emitting portion, 7220:lighting device, 7222: light-emitting portion, 7300: display device,7301: housing, 7302: display portion, 7303: operation button, 7304:display portion pull, 7305: control portion, 7400: mobile phone, 7401:housing, 7402: display portion, 7403: operation button, 7404: externalconnection port, 7405: speaker, 7406: microphone.

The invention claimed is:
 1. A display device comprising: a firstflexible display panel; a second flexible display panel; a thirdflexible display panel; a fourth flexible display panel; wherein each ofthe first flexible display panel to the fourth flexible display panelcomprises a first region configured to display an image, a second regionhaving a light-transmitting property, and a third region provided with afirst flexible printed circuit (FPC), wherein in each of the firstflexible display panel to the fourth flexible display panel the firstregion is positioned between the second region and the third region,wherein the first region of the first flexible display panel overlapswith each of the second region of the second flexible display panel andthe second region of the third flexible display panel, but does notoverlap with the second region of the fourth flexible display panel,wherein the first region of the second flexible display panel overlapswith the second region of the fourth flexible display panel, wherein thefirst region of the third flexible display panel overlaps with each ofthe second region of the first flexible display panel and the secondregion of the fourth flexible display panel, but does not overlap withthe second region of the second flexible display panel, and wherein thethird region of each of the first flexible display panel to the fourthflexible display panel has a curved region.
 2. The display deviceaccording to claim 1, wherein a display luminance is configured to belocally increased in a region of the first flexible display panel wherethe first region of the first flexible display panel overlaps witheither of the second region of the second flexible display panel and thesecond region of the third flexible display panel.
 3. The display deviceaccording to claim 1, wherein the first regions of the first to fourthflexible display panels are placed seamlessly.
 4. The display deviceaccording to claim 1, further comprising a touch panel.
 5. The displaydevice according to claim 1, wherein the display device is one of atelevision device, a digital signage, and a public information display.